Optimize build and reduce logging (#1772)

* Reduce logging

* Reduce logging

* Reduce logging

* Reduce logging

* Reduce logging

* Optimize build

* Remove testng from core-java

algorithms/pom.xml

@@ -76,6 +76,17 @@
 					</instrumentation>
 				</configuration>
 			</plugin>
+
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-surefire-plugin</artifactId>
+				<configuration>
+					<excludes>
+						<exclude>**/*LongRunningUnitTest.java</exclude>
+						<exclude>**/*IntegrationTest.java</exclude>
+					</excludes>
+				</configuration>
+			</plugin>
 		</plugins>
 	</reporting>
 </project>

algorithms/src/test/java/algorithms/AntColonyOptimizationLongRunningUnitTest.java

@@ -0,0 +1,22 @@
+package algorithms;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.algorithms.ga.ant_colony.AntColonyOptimization;
+
+public class AntColonyOptimizationLongRunningUnitTest {
+
+    @Test
+    public void testGenerateRandomMatrix() {
+        AntColonyOptimization antTSP = new AntColonyOptimization(5);
+        Assert.assertNotNull(antTSP.generateRandomMatrix(5));
+    }
+
+    @Test
+    public void testStartAntOptimization() {
+        AntColonyOptimization antTSP = new AntColonyOptimization(5);
+        Assert.assertNotNull(antTSP.solve());
+    }
+
+}

algorithms/src/test/java/algorithms/AntColonyOptimizationTest.java

@@ -1,22 +0,0 @@
-package algorithms;
-
-import org.junit.Assert;
-import org.junit.Test;
-
-import com.baeldung.algorithms.ga.ant_colony.AntColonyOptimization;
-
-public class AntColonyOptimizationTest {
-
-	@Test
-	public void testGenerateRandomMatrix() {
-		AntColonyOptimization antTSP = new AntColonyOptimization(5);
-		Assert.assertNotNull(antTSP.generateRandomMatrix(5));
-	}
-
-	@Test
-	public void testStartAntOptimization() {
-		AntColonyOptimization antTSP = new AntColonyOptimization(5);
-		Assert.assertNotNull(antTSP.solve());
-	}
-
-}

algorithms/src/test/java/algorithms/BinaryGeneticAlgorithmLongRunningUnitTest.java

@@ -0,0 +1,16 @@
+package algorithms;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.algorithms.ga.binary.SimpleGeneticAlgorithm;
+
+public class BinaryGeneticAlgorithmLongRunningUnitTest {
+
+    @Test
+    public void testGA() {
+        SimpleGeneticAlgorithm ga = new SimpleGeneticAlgorithm();
+        Assert.assertTrue(ga.runAlgorithm(50, "1011000100000100010000100000100111001000000100000100000000001111"));
+    }
+
+}

algorithms/src/test/java/algorithms/BinaryGeneticAlgorithmUnitTest.java

@@ -1,16 +0,0 @@
-package algorithms;
-
-import org.junit.Assert;
-import org.junit.Test;
-
-import com.baeldung.algorithms.ga.binary.SimpleGeneticAlgorithm;
-
-public class BinaryGeneticAlgorithmUnitTest {
-
-	@Test
-	public void testGA() {
-		SimpleGeneticAlgorithm ga = new SimpleGeneticAlgorithm();
-		Assert.assertTrue(ga.runAlgorithm(50, "1011000100000100010000100000100111001000000100000100000000001111"));
-	}
-
-}

algorithms/src/test/java/algorithms/DijkstraAlgorithmLongRunningUnitTest.java

@@ -1,76 +1,86 @@
-package algorithms;
+package algorithms;
-
+
-import org.junit.Test;
+import org.junit.Test;
-
+
-import com.baeldung.algorithms.ga.dijkstra.Dijkstra;
+import com.baeldung.algorithms.ga.dijkstra.Dijkstra;
-import com.baeldung.algorithms.ga.dijkstra.Graph;
+import com.baeldung.algorithms.ga.dijkstra.Graph;
-import com.baeldung.algorithms.ga.dijkstra.Node;
+import com.baeldung.algorithms.ga.dijkstra.Node;
-
+
-import java.util.Arrays;
+import java.util.Arrays;
-import java.util.List;
+import java.util.List;
-
+
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertTrue;
-
+
-public class DijkstraAlgorithmTest {
+public class DijkstraAlgorithmLongRunningUnitTest {
-
+
-    @Test
+    @Test
-    public void whenSPPSolved_thenCorrect() {
+    public void whenSPPSolved_thenCorrect() {
-
+
-        Node nodeA = new Node("A");
+        Node nodeA = new Node("A");
-        Node nodeB = new Node("B");
+        Node nodeB = new Node("B");
-        Node nodeC = new Node("C");
+        Node nodeC = new Node("C");
-        Node nodeD = new Node("D");
+        Node nodeD = new Node("D");
-        Node nodeE = new Node("E");
+        Node nodeE = new Node("E");
-        Node nodeF = new Node("F");
+        Node nodeF = new Node("F");
-
+
-        nodeA.addDestination(nodeB, 10);
+        nodeA.addDestination(nodeB, 10);
-        nodeA.addDestination(nodeC, 15);
+        nodeA.addDestination(nodeC, 15);
-
+
-        nodeB.addDestination(nodeD, 12);
+        nodeB.addDestination(nodeD, 12);
-        nodeB.addDestination(nodeF, 15);
+        nodeB.addDestination(nodeF, 15);
-
+
-        nodeC.addDestination(nodeE, 10);
+        nodeC.addDestination(nodeE, 10);
-
+
-        nodeD.addDestination(nodeE, 2);
+        nodeD.addDestination(nodeE, 2);
-        nodeD.addDestination(nodeF, 1);
+        nodeD.addDestination(nodeF, 1);
-
+
-        nodeF.addDestination(nodeE, 5);
+        nodeF.addDestination(nodeE, 5);
-
+
-        Graph graph = new Graph();
+        Graph graph = new Graph();
-
+
-        graph.addNode(nodeA);
+        graph.addNode(nodeA);
-        graph.addNode(nodeB);
+        graph.addNode(nodeB);
-        graph.addNode(nodeC);
+        graph.addNode(nodeC);
-        graph.addNode(nodeD);
+        graph.addNode(nodeD);
-        graph.addNode(nodeE);
+        graph.addNode(nodeE);
-        graph.addNode(nodeF);
+        graph.addNode(nodeF);
-
+
-        graph = Dijkstra.calculateShortestPathFromSource(graph, nodeA);
+        graph = Dijkstra.calculateShortestPathFromSource(graph, nodeA);
-
+
-        List<Node> shortestPathForNodeB = Arrays.asList(nodeA);
+        List<Node> shortestPathForNodeB = Arrays.asList(nodeA);
-        List<Node> shortestPathForNodeC = Arrays.asList(nodeA);
+        List<Node> shortestPathForNodeC = Arrays.asList(nodeA);
-        List<Node> shortestPathForNodeD = Arrays.asList(nodeA, nodeB);
+        List<Node> shortestPathForNodeD = Arrays.asList(nodeA, nodeB);
-        List<Node> shortestPathForNodeE = Arrays.asList(nodeA, nodeB, nodeD);
+        List<Node> shortestPathForNodeE = Arrays.asList(nodeA, nodeB, nodeD);
-        List<Node> shortestPathForNodeF = Arrays.asList(nodeA, nodeB, nodeD);
+        List<Node> shortestPathForNodeF = Arrays.asList(nodeA, nodeB, nodeD);
-
+
-        for (Node node : graph.getNodes()) {
+        for (Node node : graph.getNodes()) {
-            switch (node.getName()) {
+            switch (node.getName()) {
-            case "B":
+            case "B":
-                assertTrue(node.getShortestPath().equals(shortestPathForNodeB));
+                assertTrue(node
-                break;
+                  .getShortestPath()
-            case "C":
+                  .equals(shortestPathForNodeB));
-                assertTrue(node.getShortestPath().equals(shortestPathForNodeC));
+                break;
-                break;
+            case "C":
-            case "D":
+                assertTrue(node
-                assertTrue(node.getShortestPath().equals(shortestPathForNodeD));
+                  .getShortestPath()
-                break;
+                  .equals(shortestPathForNodeC));
-            case "E":
+                break;
-                assertTrue(node.getShortestPath().equals(shortestPathForNodeE));
+            case "D":
-                break;
+                assertTrue(node
-            case "F":
+                  .getShortestPath()
-                assertTrue(node.getShortestPath().equals(shortestPathForNodeF));
+                  .equals(shortestPathForNodeD));
-                break;
+                break;
-            }
+            case "E":
-        }
+                assertTrue(node
-    }
+                  .getShortestPath()
-}
+                  .equals(shortestPathForNodeE));
+                break;
+            case "F":
+                assertTrue(node
+                  .getShortestPath()
+                  .equals(shortestPathForNodeF));
+                break;
+            }
+        }
+    }
+}

algorithms/src/test/java/algorithms/RtFiniteStateMachineLongRunningUnitTest.java

@@ -1,38 +1,37 @@
 package algorithms;
 
-import static org.junit.Assert.*;
-import org.junit.Test;
 import com.baeldung.automata.*;
+import org.junit.Test;
 
-/**
+import static org.junit.Assert.assertTrue;
- * Tests for {@link RtFiniteStateMachine}
+
- */
+public final class RtFiniteStateMachineLongRunningUnitTest {
-public final class RtFiniteStateMachineTest {
 
     @Test
     public void acceptsSimplePair() {
         String json = "{\"key\":\"value\"}";
         FiniteStateMachine machine = this.buildJsonStateMachine();
-        for (int i=0;i<json.length();i++) {
+        for (int i = 0; i < json.length(); i++) {
             machine = machine.switchState(String.valueOf(json.charAt(i)));
         }
         assertTrue(machine.canStop());
     }
+
     @Test
     public void acceptsMorePairs() {
         String json = "{\"key1\":\"value1\",\"key2\":\"value2\"}";
         FiniteStateMachine machine = this.buildJsonStateMachine();
-        for (int i=0;i<json.length();i++) {
+        for (int i = 0; i < json.length(); i++) {
             machine = machine.switchState(String.valueOf(json.charAt(i)));
         }
         assertTrue(machine.canStop());
     }
-    
+
     @Test(expected = IllegalArgumentException.class)
     public void missingColon() {
         String json = "{\"key\"\"value\"}";
         FiniteStateMachine machine = this.buildJsonStateMachine();
-        for (int i=0;i<json.length();i++) {
+        for (int i = 0; i < json.length(); i++) {
             machine = machine.switchState(String.valueOf(json.charAt(i)));
         }
     }
@@ -56,20 +55,12 @@ public final class RtFiniteStateMachineTest {
         second.with(new RtTransition("\"", third));
         //Add transitions with chars 0-9 and a-z
         for (int i = 0; i < 26; i++) {
-            if(i<10) {
+            if (i < 10) {
-                third = third.with(
+                third = third.with(new RtTransition(String.valueOf(i), third));
-                    new RtTransition(String.valueOf(i), third)
+                sixth = sixth.with(new RtTransition(String.valueOf(i), sixth));
-                );
-                sixth = sixth.with(
-                    new RtTransition(String.valueOf(i), sixth)
-                );
             }
-            third = third.with(
+            third = third.with(new RtTransition(String.valueOf((char) ('a' + i)), third));
-                new RtTransition(String.valueOf((char) ('a' + i)), third)
+            sixth = sixth.with(new RtTransition(String.valueOf((char) ('a' + i)), sixth));
-            );
-            sixth = sixth.with(
-                new RtTransition(String.valueOf((char) ('a' + i)), sixth)
-            );
         }
         third.with(new RtTransition("\"", fourth));
         fourth.with(new RtTransition(":", fifth));

algorithms/src/test/java/algorithms/SimulatedAnnealingLongRunningUnitTest.java

@@ -5,7 +5,7 @@ import org.junit.Test;
 
 import com.baeldung.algorithms.ga.annealing.SimulatedAnnealing;
 
-public class SimulatedAnnealingTest {
+public class SimulatedAnnealingLongRunningUnitTest {
 
     @Test
     public void testSimulateAnnealing() {

algorithms/src/test/java/com/baeldung/algorithms/primechecker/BigIntegerPrimeCheckerTest.java

@@ -1,28 +0,0 @@
-package com.baeldung.algorithms.primechecker;
-
-import static org.junit.Assert.assertTrue;
-
-import org.junit.Test;
-
-import com.baeldung.algorithms.primechecker.BigIntegerPrimeChecker;
-import com.baeldung.algorithms.primechecker.PrimeChecker;
-
-public class BigIntegerPrimeCheckerTest {
-
-    BigIntegerPrimeChecker primeChecker = new BigIntegerPrimeChecker();
-    
-    @Test
-    public void givenPrimeNumber_whenCheckIsPrime_thenTrue(){
-        assertTrue(primeChecker.isPrime(13l));
-        assertTrue(primeChecker.isPrime(1009L));
-        assertTrue(primeChecker.isPrime(74207281L));
-    }
-    
-    @Test
-    public void givenNonPrimeNumber_whenCheckIsPrime_thenFalse(){
-        assertTrue(!primeChecker.isPrime(50L));
-        assertTrue(!primeChecker.isPrime(1001L));
-        assertTrue(!primeChecker.isPrime(74207282L));
-    }
-    
-}

algorithms/src/test/java/com/baeldung/algorithms/primechecker/BruteForcePrimeCheckerTest.java

@@ -1,27 +0,0 @@
-package com.baeldung.algorithms.primechecker;
-
-import org.junit.Test;
-
-import com.baeldung.algorithms.primechecker.BruteForcePrimeChecker;
-
-import static org.junit.Assert.*;
-
-public class BruteForcePrimeCheckerTest {
-
-    BruteForcePrimeChecker primeChecker = new BruteForcePrimeChecker();
-    
-    @Test
-    public void givenPrimeNumber_whenCheckIsPrime_thenTrue(){
-        assertTrue(primeChecker.isPrime(13));
-        assertTrue(primeChecker.isPrime(1009));
-    }
-    
-    @Test
-    public void givenNonPrimeNumber_whenCheckIsPrime_thenFalse(){
-        assertTrue(!primeChecker.isPrime(50));
-        assertTrue(!primeChecker.isPrime(1001));
-    }
-    
-    
-    
-}

algorithms/src/test/java/com/baeldung/algorithms/primechecker/OptimisedPrimeCheckerTest.java

@@ -1,26 +0,0 @@
-package com.baeldung.algorithms.primechecker;
-
-import static org.junit.Assert.assertTrue;
-
-import org.junit.Test;
-
-import com.baeldung.algorithms.primechecker.OptimisedPrimeChecker;
-import com.baeldung.algorithms.primechecker.PrimeChecker;
-
-public class OptimisedPrimeCheckerTest {
-
-    OptimisedPrimeChecker primeChecker = new OptimisedPrimeChecker();
-    
-    @Test
-    public void givenPrimeNumber_whenCheckIsPrime_thenTrue(){
-        assertTrue(primeChecker.isPrime(13));
-        assertTrue(primeChecker.isPrime(1009));
-    }
-    
-    @Test
-    public void givenNonPrimeNumber_whenCheckIsPrime_thenFalse(){
-        assertTrue(!primeChecker.isPrime(50));
-        assertTrue(!primeChecker.isPrime(1001));
-    }
-    
-}

algorithms/src/test/java/com/baeldung/algorithms/primechecker/PrimeCheckerTest.java

@@ -0,0 +1,69 @@
+package com.baeldung.algorithms.primechecker;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class PrimeCheckerTest {
+
+    private final BigIntegerPrimeChecker primeChecker = new BigIntegerPrimeChecker();
+    
+    @Test
+    public void whenCheckIsPrime_thenTrue(){
+        assertTrue(primeChecker.isPrime(13l));
+        assertTrue(primeChecker.isPrime(1009L));
+        assertTrue(primeChecker.isPrime(74207281L));
+    }
+    
+    @Test
+    public void whenCheckIsPrime_thenFalse(){
+        assertTrue(!primeChecker.isPrime(50L));
+        assertTrue(!primeChecker.isPrime(1001L));
+        assertTrue(!primeChecker.isPrime(74207282L));
+    }
+
+    private final BruteForcePrimeChecker bfPrimeChecker = new BruteForcePrimeChecker();
+
+    @Test
+    public void whenBFCheckIsPrime_thenTrue(){
+        assertTrue(bfPrimeChecker.isPrime(13));
+        assertTrue(bfPrimeChecker.isPrime(1009));
+    }
+
+    @Test
+    public void whenBFCheckIsPrime_thenFalse(){
+        assertFalse(bfPrimeChecker.isPrime(50));
+        assertFalse(bfPrimeChecker.isPrime(1001));
+    }
+
+
+    private final OptimisedPrimeChecker optimisedPrimeChecker = new OptimisedPrimeChecker();
+
+    @Test
+    public void whenOptCheckIsPrime_thenTrue(){
+        assertTrue(optimisedPrimeChecker.isPrime(13));
+        assertTrue(optimisedPrimeChecker.isPrime(1009));
+    }
+
+    @Test
+    public void whenOptCheckIsPrime_thenFalse(){
+        assertFalse(optimisedPrimeChecker.isPrime(50));
+        assertFalse(optimisedPrimeChecker.isPrime(1001));
+    }
+
+    private final PrimesPrimeChecker primesPrimeChecker = new PrimesPrimeChecker();
+
+    @Test
+    public void whenPrimesCheckIsPrime_thenTrue() {
+        assertTrue(primesPrimeChecker.isPrime(13));
+        assertTrue(primesPrimeChecker.isPrime(1009));
+    }
+
+    @Test
+    public void whenPrimesCheckIsPrime_thenFalse() {
+        assertFalse(primesPrimeChecker.isPrime(50));
+        assertFalse(primesPrimeChecker.isPrime(1001));
+    }
+    
+}

algorithms/src/test/java/com/baeldung/algorithms/primechecker/PrimesPrimeCheckerTest.java

@@ -1,25 +0,0 @@
-package com.baeldung.algorithms.primechecker;
-
-import static org.junit.Assert.assertTrue;
-
-import org.junit.Test;
-
-import com.baeldung.algorithms.primechecker.PrimeChecker;
-import com.baeldung.algorithms.primechecker.PrimesPrimeChecker;
-
-public class PrimesPrimeCheckerTest {
-    PrimesPrimeChecker primeChecker = new PrimesPrimeChecker();
-
-    @Test
-    public void givenPrimeNumber_whenCheckIsPrime_thenTrue() {
-        assertTrue(primeChecker.isPrime(13));
-        assertTrue(primeChecker.isPrime(1009));
-    }
-
-    @Test
-    public void givenNonPrimeNumber_whenCheckIsPrime_thenFalse() {
-        assertTrue(!primeChecker.isPrime(50));
-        assertTrue(!primeChecker.isPrime(1001));
-    }
-
-}

core-java/pom.xml

@@ -135,13 +135,6 @@
             <scope>test</scope>
         </dependency>
 
-        <dependency>
-            <groupId>org.testng</groupId>
-            <artifactId>testng</artifactId>
-            <version>${testng.version}</version>
-            <scope>test</scope>
-        </dependency>
-
         <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-core</artifactId>

core-java/src/main/java/com/baeldung/concurrent/sleepwait/ThreadA.java

@@ -1,9 +1,15 @@
 package com.baeldung.concurrent.sleepwait;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /***
  * Example of waking up a waiting thread
  */
 public class ThreadA {
+
+    private static final Logger LOG = LoggerFactory.getLogger(ThreadA.class);
+
     private static final ThreadB b = new ThreadB();
 
     public static void main(String... args) throws InterruptedException {
@@ -11,11 +17,11 @@ public class ThreadA {
 
         synchronized (b) {
             while (b.sum == 0) {
-                System.out.println("Waiting for ThreadB to complete...");
+                LOG.debug("Waiting for ThreadB to complete...");
                 b.wait();
             }
 
-            System.out.println("ThreadB has completed. Sum from that thread is: " + b.sum);
+            LOG.debug("ThreadB has completed. Sum from that thread is: " + b.sum);
         }
     }
 }

core-java/src/main/java/com/baeldung/concurrent/sleepwait/WaitSleepExample.java

@@ -1,9 +1,15 @@
 package com.baeldung.concurrent.sleepwait;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /***
  * Example of wait() and sleep() methods
  */
 public class WaitSleepExample {
+
+    private static final Logger LOG = LoggerFactory.getLogger(WaitSleepExample.class);
+
     private static final Object LOCK = new Object();
 
     public static void main(String... args) throws InterruptedException {
@@ -12,11 +18,11 @@ public class WaitSleepExample {
 
     private static void sleepWaitInSyncronizedBlocks() throws InterruptedException {
         Thread.sleep(1000); // called on the thread
-        System.out.println("Thread '" + Thread.currentThread().getName() + "' is woken after sleeping for 1 second");
+        LOG.debug("Thread '" + Thread.currentThread().getName() + "' is woken after sleeping for 1 second");
 
         synchronized (LOCK) {
             LOCK.wait(1000); // called on the object, synchronization required
-            System.out.println("Object '" + LOCK + "' is woken after waiting for 1 second");
+            LOG.debug("Object '" + LOCK + "' is woken after waiting for 1 second");
         }
     }
     

core-java/src/main/java/com/baeldung/dirmonitoring/DirectoryMonitoringExample.java

@@ -1,14 +1,19 @@
 package com.baeldung.dirmonitoring;
 
-import java.io.File;
-
 import org.apache.commons.io.monitor.FileAlterationListener;
 import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
 import org.apache.commons.io.monitor.FileAlterationMonitor;
 import org.apache.commons.io.monitor.FileAlterationObserver;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
 
 public class DirectoryMonitoringExample {
 
+    private static final Logger LOG = LoggerFactory.getLogger(DirectoryMonitoringExample.class);
+
+
     public static final int POLL_INTERVAL = 500;
 
     public static void main(String[] args) throws Exception {
@@ -17,17 +22,17 @@ public class DirectoryMonitoringExample {
         FileAlterationListener listener = new FileAlterationListenerAdaptor() {
             @Override
             public void onFileCreate(File file) {
-                System.out.println("File: " + file.getName() + " created");
+                LOG.debug("File: " + file.getName() + " created");
             }
 
             @Override
             public void onFileDelete(File file) {
-                System.out.println("File: " + file.getName() + " deleted");
+                LOG.debug("File: " + file.getName() + " deleted");
             }
 
             @Override
             public void onFileChange(File file) {
-                System.out.println("File: " + file.getName() + " changed");
+                LOG.debug("File: " + file.getName() + " changed");
             }
         };
         observer.addListener(listener);

core-java/src/main/java/com/baeldung/doublecolon/MacbookPro.java

@@ -1,9 +1,14 @@
 package com.baeldung.doublecolon;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.function.Function;
 
 public class MacbookPro extends Computer {
 
+    private static final Logger LOG = LoggerFactory.getLogger(MacbookPro.class);
+
     public MacbookPro(int age, String color) {
         super(age, color);
     }
@@ -14,12 +19,12 @@ public class MacbookPro extends Computer {
 
     @Override
     public void turnOnPc() {
-        System.out.println("MacbookPro turned on");
+        LOG.debug("MacbookPro turned on");
     }
 
     @Override
     public void turnOffPc() {
-        System.out.println("MacbookPro turned off");
+        LOG.debug("MacbookPro turned off");
     }
 
     @Override
@@ -27,7 +32,7 @@ public class MacbookPro extends Computer {
 
         Function<Double, Double> function = super::calculateValue;
         final Double pcValue = function.apply(initialValue);
-        System.out.println("First value is:" + pcValue);
+        LOG.debug("First value is:" + pcValue);
         return pcValue + (initialValue / 10);
 
     }

core-java/src/main/java/com/baeldung/java/map/MyKey.java

@@ -1,6 +1,11 @@
 package com.baeldung.java.map;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 public class MyKey {
+    private static final Logger LOG = LoggerFactory.getLogger(MyKey.class);
+    
     private String name;
     private int id;
 
@@ -27,7 +32,7 @@ public class MyKey {
 
     @Override
     public int hashCode() {
-        System.out.println("Calling hashCode()");
+        LOG.debug("Calling hashCode()");
         return id;
     }
 
@@ -38,7 +43,7 @@ public class MyKey {
 
     @Override
     public boolean equals(Object obj) {
-        System.out.println("Calling equals() for key: " + obj);
+        LOG.debug("Calling equals() for key: " + obj);
         if (this == obj)
             return true;
         if (obj == null)

core-java/src/main/java/com/baeldung/jmx/Game.java

@@ -1,23 +1,28 @@
 package com.baeldung.jmx;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 public class Game implements GameMBean {
 
+    private static final Logger LOG = LoggerFactory.getLogger(Game.class);
+
     private String playerName;
 
     @Override
     public void playFootball(String clubName) {
-        System.out.println(this.playerName + " playing football for " + clubName);
+        LOG.debug(this.playerName + " playing football for " + clubName);
     }
 
     @Override
     public String getPlayerName() {
-        System.out.println("Return playerName " + this.playerName);
+        LOG.debug("Return playerName " + this.playerName);
         return playerName;
     }
 
     @Override
     public void setPlayerName(String playerName) {
-        System.out.println("Set playerName to value " + playerName);
+        LOG.debug("Set playerName to value " + playerName);
         this.playerName = playerName;
     }
 

core-java/src/main/java/com/baeldung/jmx/JMXTutorialMainlauncher.java

@@ -1,19 +1,20 @@
 package com.baeldung.jmx;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.*;
 import java.lang.management.ManagementFactory;
-import javax.management.InstanceAlreadyExistsException;
-import javax.management.MBeanRegistrationException;
-import javax.management.MBeanServer;
-import javax.management.MalformedObjectNameException;
-import javax.management.NotCompliantMBeanException;
-import javax.management.ObjectName;
 
 public class JMXTutorialMainlauncher {
 
+    private static final Logger LOG = LoggerFactory.getLogger(JMXTutorialMainlauncher.class);
+
+
     public static void main(String[] args) {
         // TODO Auto-generated method stub
 
-        System.out.println("This is basic JMX tutorial");
+        LOG.debug("This is basic JMX tutorial");
         ObjectName objectName = null;
         try {
             objectName = new ObjectName("com.baeldung.tutorial:type=basic,name=game");
@@ -27,8 +28,8 @@ public class JMXTutorialMainlauncher {
         } catch (InstanceAlreadyExistsException | MBeanRegistrationException | NotCompliantMBeanException e) {
             e.printStackTrace();
         }
-        System.out.println("Registration for Game mbean with the platform server is successfull");
+        LOG.debug("Registration for Game mbean with the platform server is successfull");
-        System.out.println("Please open jconsole to access Game mbean");
+        LOG.debug("Please open jconsole to access Game mbean");
         while (true) {
             // to ensure application does not terminate
         }

core-java/src/main/java/com/baeldung/socket/EchoClient.java

@@ -1,9 +1,16 @@
 package com.baeldung.socket;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.*;
 import java.net.*;
 
 public class EchoClient {
+
+
+    private static final Logger LOG = LoggerFactory.getLogger(EchoClient.class);
+    
     private Socket clientSocket;
     private PrintWriter out;
     private BufferedReader in;
@@ -14,7 +21,7 @@ public class EchoClient {
             out = new PrintWriter(clientSocket.getOutputStream(), true);
             in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
         } catch (IOException e) {
-            System.out.print(e);
+            LOG.debug("Error when initializing connection", e);
         }
 
     }
@@ -34,7 +41,7 @@ public class EchoClient {
             out.close();
             clientSocket.close();
         } catch (IOException e) {
-            e.printStackTrace();
+            LOG.debug("error when closing", e);
         }
 
     }

core-java/src/main/java/com/baeldung/socket/EchoMultiServer.java

@@ -1,9 +1,15 @@
 package com.baeldung.socket;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.net.*;
 import java.io.*;
 
 public class EchoMultiServer {
+
+    private static final Logger LOG = LoggerFactory.getLogger(EchoMultiServer.class);
+
     private ServerSocket serverSocket;
 
     public void start(int port) {
@@ -57,7 +63,7 @@ public class EchoMultiServer {
                 clientSocket.close();
 
             } catch (IOException e) {
-                e.printStackTrace();
+                LOG.debug(e.getMessage());
             }
         }
     }

core-java/src/main/java/com/baeldung/socket/EchoServer.java

@@ -1,9 +1,15 @@
 package com.baeldung.socket;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.net.*;
 import java.io.*;
 
 public class EchoServer {
+
+    private static final Logger LOG = LoggerFactory.getLogger(EchoServer.class);
+
     private ServerSocket serverSocket;
     private Socket clientSocket;
     private PrintWriter out;
@@ -24,7 +30,7 @@ public class EchoServer {
                 out.println(inputLine);
             }
         } catch (IOException e) {
-            e.printStackTrace();
+            LOG.debug(e.getMessage());
         }
 
     }
@@ -36,7 +42,7 @@ public class EchoServer {
             clientSocket.close();
             serverSocket.close();
         } catch (IOException e) {
-            e.printStackTrace();
+            LOG.debug(e.getMessage());
         }
 
     }

core-java/src/main/java/com/baeldung/socket/GreetClient.java

@@ -1,5 +1,8 @@
 package com.baeldung.socket;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
@@ -7,6 +10,9 @@ import java.io.PrintWriter;
 import java.net.Socket;
 
 public class GreetClient {
+
+    private static final Logger LOG = LoggerFactory.getLogger(EchoMultiServer.class);
+
     private Socket clientSocket;
     private PrintWriter out;
     private BufferedReader in;
@@ -17,7 +23,7 @@ public class GreetClient {
             out = new PrintWriter(clientSocket.getOutputStream(), true);
             in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
         } catch (IOException e) {
-
+            LOG.debug(e.getMessage());
         }
 
     }
@@ -37,7 +43,7 @@ public class GreetClient {
             out.close();
             clientSocket.close();
         } catch (IOException e) {
-            e.printStackTrace();
+            LOG.debug(e.getMessage());
         }
     }
 

core-java/src/main/java/com/baeldung/socket/GreetServer.java

@@ -1,9 +1,15 @@
 package com.baeldung.socket;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.net.*;
 import java.io.*;
 
 public class GreetServer {
+
+    private static final Logger LOG = LoggerFactory.getLogger(GreetServer.class);
+
     private ServerSocket serverSocket;
     private Socket clientSocket;
     private PrintWriter out;
@@ -21,7 +27,7 @@ public class GreetServer {
             else
                 out.println("unrecognised greeting");
         } catch (IOException e) {
-            e.printStackTrace();
+            LOG.debug(e.getMessage());
         }
 
     }
@@ -33,7 +39,7 @@ public class GreetServer {
             clientSocket.close();
             serverSocket.close();
         } catch (IOException e) {
-            e.printStackTrace();
+            LOG.debug(e.getMessage());
         }
 
     }

core-java/src/main/java/com/baeldung/stream/InfiniteStreams.java

@@ -1,9 +1,15 @@
 package com.baeldung.stream;
 
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.stream.Stream;
 
 public class InfiniteStreams {
+
+    private static final Logger LOG = LoggerFactory.getLogger(InfiniteStreams.class);
+
     public static void main(String[] args) {
         doWhileOldWay();
 
@@ -15,7 +21,7 @@ public class InfiniteStreams {
 
         int i = 0;
         while (i < 10) {
-            System.out.println(i);
+            LOG.debug("{}", i);
             i++;
         }
     }

core-java/src/main/java/com/baeldung/threadlocal/ThreadLocalWithUserContext.java

@@ -1,7 +1,11 @@
 package com.baeldung.threadlocal;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class ThreadLocalWithUserContext implements Runnable {
+    private static final Logger LOG = LoggerFactory.getLogger(ThreadLocalWithUserContext.class);
+    
     private static final ThreadLocal<Context> userContext = new ThreadLocal<>();
     private final Integer userId;
     private UserRepository userRepository = new UserRepository();
@@ -15,6 +19,6 @@ public class ThreadLocalWithUserContext implements Runnable {
     public void run() {
         String userName = userRepository.getUserNameForUserId(userId);
         userContext.set(new Context(userName));
-        System.out.println("thread context for given userId: " + userId + " is: " + userContext.get());
+        LOG.debug("thread context for given userId: " + userId + " is: " + userContext.get());
     }
 }

core-java/src/main/java/com/baeldung/transferqueue/Consumer.java

@@ -1,9 +1,15 @@
 package com.baeldung.transferqueue;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.concurrent.TransferQueue;
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class Consumer implements Runnable {
+    private static final Logger LOG = LoggerFactory.getLogger(Consumer.class);
+
+    
     private final TransferQueue<String> transferQueue;
     private final String name;
     private final int numberOfMessagesToConsume;
@@ -19,10 +25,10 @@ public class Consumer implements Runnable {
     public void run() {
         for (int i = 0; i < numberOfMessagesToConsume; i++) {
             try {
-                System.out.println("Consumer: " + name + " is waiting to take element...");
+                LOG.debug("Consumer: " + name + " is waiting to take element...");
                 String element = transferQueue.take();
                 longProcessing(element);
-                System.out.println("Consumer: " + name + " received element: " + element);
+                LOG.debug("Consumer: " + name + " received element: " + element);
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }

core-java/src/main/java/com/baeldung/transferqueue/Producer.java

@@ -1,10 +1,15 @@
 package com.baeldung.transferqueue;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TransferQueue;
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class Producer implements Runnable {
+    private static final Logger LOG = LoggerFactory.getLogger(Producer.class);
+
     private final TransferQueue<String> transferQueue;
     private final String name;
     private final Integer numberOfMessagesToProduce;
@@ -20,13 +25,13 @@ public class Producer implements Runnable {
     public void run() {
         for (int i = 0; i < numberOfMessagesToProduce; i++) {
             try {
-                System.out.println("Producer: " + name + " is waiting to transfer...");
+                LOG.debug("Producer: " + name + " is waiting to transfer...");
                 boolean added = transferQueue.tryTransfer("A" + i, 4000, TimeUnit.MILLISECONDS);
                 if (added) {
                     numberOfProducedMessages.incrementAndGet();
-                    System.out.println("Producer: " + name + " transferred element: A" + i);
+                    LOG.debug("Producer: " + name + " transferred element: A" + i);
                 } else {
-                    System.out.println("can not add an element due to the timeout");
+                    LOG.debug("can not add an element due to the timeout");
                 }
             } catch (InterruptedException e) {
                 e.printStackTrace();

core-java/src/test/java/com/baeldung/PrimitiveConversionsJUnitTest.java

@@ -1,13 +1,14 @@
 package com.baeldung;
 
 import org.junit.Test;
-import static org.junit.Assert.*;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.junit.Assert.assertEquals;
 
-/**
- *
- * @author paulo.motta
- */
 public class PrimitiveConversionsJUnitTest {
+
+    private static final Logger LOG = LoggerFactory.getLogger(PrimitiveConversionsJUnitTest.class);
     
     @Test
     public void givenDataWithLessBits_whenAttributingToLargerSizeVariable_thenNoSpecialNotation() {
@@ -60,36 +61,36 @@ public class PrimitiveConversionsJUnitTest {
     @Test
     public void givenByteValue_whenConvertingToChar_thenWidenAndNarrowTakesPlace(){
         byte myLargeValueByte = (byte) 130;   //0b10000010
-        System.out.println(myLargeValueByte); //0b10000010 -126
+        LOG.debug("{}", myLargeValueByte); //0b10000010 -126
         assertEquals( -126, myLargeValueByte);
         
         int myLargeValueInt = myLargeValueByte;
-        System.out.println(myLargeValueInt); //0b11111111 11111111 11111111 10000010 -126
+        LOG.debug("{}", myLargeValueInt); //0b11111111 11111111 11111111 10000010 -126
         assertEquals( -126, myLargeValueInt);
         
         char myLargeValueChar = (char) myLargeValueByte;
-        System.out.println(myLargeValueChar);//0b11111111 10000010 unsigned 0xFF82
+        LOG.debug("{}", myLargeValueChar);//0b11111111 10000010 unsigned 0xFF82
         assertEquals(0xFF82, myLargeValueChar);
         
         myLargeValueInt = myLargeValueChar;
-        System.out.println(myLargeValueInt); //0b11111111 10000010  65410
+        LOG.debug("{}", myLargeValueInt); //0b11111111 10000010  65410
         assertEquals(65410, myLargeValueInt);
         
         byte myOtherByte = (byte) myLargeValueInt;
-        System.out.println(myOtherByte); //0b10000010 -126
+        LOG.debug("{}", myOtherByte); //0b10000010 -126
         assertEquals( -126, myOtherByte);
         
         
         char myLargeValueChar2 = 130; //This is an int not a byte!
-        System.out.println(myLargeValueChar2);//0b00000000 10000010 unsigned 0x0082
+        LOG.debug("{}", myLargeValueChar2);//0b00000000 10000010 unsigned 0x0082
         assertEquals(0x0082, myLargeValueChar2);
         
         int myLargeValueInt2 = myLargeValueChar2;
-        System.out.println(myLargeValueInt2); //0b00000000 10000010  130
+        LOG.debug("{}", myLargeValueInt2); //0b00000000 10000010  130
         assertEquals(130, myLargeValueInt2);
         
         byte myOtherByte2 = (byte) myLargeValueInt2;
-        System.out.println(myOtherByte2); //0b10000010 -126
+        LOG.debug("{}", myOtherByte2); //0b10000010 -126
         assertEquals( -126, myOtherByte2);
     }
     

core-java/src/test/java/com/baeldung/completablefuture/CompletableFutureUnitTest.java

@@ -1,20 +1,21 @@
 package com.baeldung.completablefuture;
 
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
-import java.util.concurrent.CancellationException;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Executors;
-import java.util.concurrent.Future;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
-import org.junit.Test;
-
 public class CompletableFutureUnitTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(CompletableFutureUnitTest.class);
+
+
     @Test
     public void whenRunningCompletableFutureAsynchronously_thenGetMethodWaitsForResult() throws InterruptedException, ExecutionException {
         Future<String> completableFuture = calculateAsync();
@@ -72,7 +73,7 @@ public class CompletableFutureUnitTest {
     public void whenAddingThenAcceptToFuture_thenFunctionExecutesAfterComputationIsFinished() throws ExecutionException, InterruptedException {
         CompletableFuture<String> completableFuture = CompletableFuture.supplyAsync(() -> "Hello");
 
-        CompletableFuture<Void> future = completableFuture.thenAccept(s -> System.out.println("Computation returned: " + s));
+        CompletableFuture<Void> future = completableFuture.thenAccept(s -> LOG.debug("Computation returned: " + s));
 
         future.get();
     }
@@ -81,7 +82,7 @@ public class CompletableFutureUnitTest {
     public void whenAddingThenRunToFuture_thenFunctionExecutesAfterComputationIsFinished() throws ExecutionException, InterruptedException {
         CompletableFuture<String> completableFuture = CompletableFuture.supplyAsync(() -> "Hello");
 
-        CompletableFuture<Void> future = completableFuture.thenRun(() -> System.out.println("Computation finished."));
+        CompletableFuture<Void> future = completableFuture.thenRun(() -> LOG.debug("Computation finished."));
 
         future.get();
     }
@@ -111,7 +112,7 @@ public class CompletableFutureUnitTest {
 
     @Test
     public void whenUsingThenAcceptBoth_thenWaitForExecutionOfBothFutures() throws ExecutionException, InterruptedException {
-        CompletableFuture.supplyAsync(() -> "Hello").thenAcceptBoth(CompletableFuture.supplyAsync(() -> " World"), (s1, s2) -> System.out.println(s1 + s2));
+        CompletableFuture.supplyAsync(() -> "Hello").thenAcceptBoth(CompletableFuture.supplyAsync(() -> " World"), (s1, s2) -> LOG.debug(s1 + s2));
     }
 
     @Test

core-java/src/test/java/com/baeldung/concurrent/future/SquareCalculatorIntegrationTest.java

@@ -5,6 +5,8 @@ import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TestName;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.concurrent.*;
 
@@ -13,6 +15,9 @@ import static org.junit.Assert.assertTrue;
 
 public class SquareCalculatorIntegrationTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(SquareCalculatorIntegrationTest.class);
+
+
     @Rule
     public TestName name = new TestName();
 
@@ -28,7 +33,7 @@ public class SquareCalculatorIntegrationTest {
         Future<Integer> result2 = squareCalculator.calculate(1000);
 
         while (!result1.isDone() || !result2.isDone()) {
-            System.out.println(String.format("Task 1 is %s and Task 2 is %s.", result1.isDone() ? "done" : "not done", result2.isDone() ? "done" : "not done"));
+            LOG.debug(String.format("Task 1 is %s and Task 2 is %s.", result1.isDone() ? "done" : "not done", result2.isDone() ? "done" : "not done"));
 
             Thread.sleep(300);
         }
@@ -54,7 +59,7 @@ public class SquareCalculatorIntegrationTest {
         Future<Integer> result2 = squareCalculator.calculate(1000);
 
         while (!result1.isDone() || !result2.isDone()) {
-            System.out.println(String.format("Task 1 is %s and Task 2 is %s.", result1.isDone() ? "done" : "not done", result2.isDone() ? "done" : "not done"));
+            LOG.debug(String.format("Task 1 is %s and Task 2 is %s.", result1.isDone() ? "done" : "not done", result2.isDone() ? "done" : "not done"));
 
             Thread.sleep(300);
         }
@@ -84,6 +89,6 @@ public class SquareCalculatorIntegrationTest {
 
     @After
     public void end() {
-        System.out.println(String.format("Test %s took %s ms \n", name.getMethodName(), System.currentTimeMillis() - start));
+        LOG.debug(String.format("Test %s took %s ms \n", name.getMethodName(), System.currentTimeMillis() - start));
     }
 }

core-java/src/test/java/com/baeldung/concurrent/priorityblockingqueue/PriorityBlockingQueueIntegrationTest.java

@@ -1,6 +1,8 @@
 package com.baeldung.concurrent.priorityblockingqueue;
 
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
 import java.util.concurrent.PriorityBlockingQueue;
@@ -11,6 +13,9 @@ import static org.assertj.core.util.Lists.newArrayList;
 
 public class PriorityBlockingQueueIntegrationTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(PriorityBlockingQueueIntegrationTest.class);
+
+
     @Test
     public void givenUnorderedValues_whenPolling_thenShouldOrderQueue() throws InterruptedException {
         PriorityBlockingQueue<Integer> queue = new PriorityBlockingQueue<>();
@@ -32,11 +37,11 @@ public class PriorityBlockingQueueIntegrationTest {
         PriorityBlockingQueue<Integer> queue = new PriorityBlockingQueue<>();
 
         final Thread thread = new Thread(() -> {
-            System.out.println("Polling...");
+            LOG.debug("Polling...");
             while (true) {
                 try {
                     Integer poll = queue.take();
-                    System.out.println("Polled: " + poll);
+                    LOG.debug("Polled: " + poll);
                 } catch (InterruptedException e) {
                 }
             }
@@ -44,7 +49,7 @@ public class PriorityBlockingQueueIntegrationTest {
         thread.start();
 
         Thread.sleep(TimeUnit.SECONDS.toMillis(5));
-        System.out.println("Adding to queue");
+        LOG.debug("Adding to queue");
 
         queue.addAll(newArrayList(1, 5, 6, 1, 2, 6, 7));
         Thread.sleep(TimeUnit.SECONDS.toMillis(1));

core-java/src/test/java/com/baeldung/dynamicproxy/DynamicProxyTest.java

@@ -7,7 +7,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 import static org.junit.Assert.assertEquals;
-import static org.testng.Assert.fail;
+import static org.junit.Assert.fail;
 
 public class DynamicProxyTest {
 

core-java/src/test/java/com/baeldung/functionalinterface/FunctionalInterfaceUnitTest.java

@@ -1,8 +1,9 @@
 package com.baeldung.functionalinterface;
 
-import static org.junit.Assert.assertArrayEquals;
+import com.google.common.util.concurrent.Uninterruptibles;
-import static org.junit.Assert.assertEquals;
+import org.junit.Test;
-import static org.junit.Assert.assertTrue;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.Arrays;
 import java.util.HashMap;
@@ -14,12 +15,13 @@ import java.util.function.Supplier;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.junit.Test;
+import static org.junit.Assert.*;
-
-import com.google.common.util.concurrent.Uninterruptibles;
 
 public class FunctionalInterfaceUnitTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(FunctionalInterfaceUnitTest.class);
+
+
     @Test
     public void whenPassingLambdaToComputeIfAbsent_thenTheValueGetsComputedAndPutIntoMap() {
         Map<String, Integer> nameMap = new HashMap<>();
@@ -65,7 +67,7 @@ public class FunctionalInterfaceUnitTest {
 
     @Test
     public void whenPassingLambdaToThreadConstructor_thenLambdaInferredToRunnable() {
-        Thread thread = new Thread(() -> System.out.println("Hello From Another Thread"));
+        Thread thread = new Thread(() -> LOG.debug("Hello From Another Thread"));
         thread.start();
     }
 
@@ -93,7 +95,7 @@ public class FunctionalInterfaceUnitTest {
     @Test
     public void whenUsingConsumerInForEach_thenConsumerExecutesForEachListElement() {
         List<String> names = Arrays.asList("John", "Freddy", "Samuel");
-        names.forEach(name -> System.out.println("Hello, " + name));
+        names.forEach(name -> LOG.debug("Hello, " + name));
     }
 
     @Test
@@ -103,7 +105,7 @@ public class FunctionalInterfaceUnitTest {
         ages.put("Freddy", 24);
         ages.put("Samuel", 30);
 
-        ages.forEach((name, age) -> System.out.println(name + " is " + age + " years old"));
+        ages.forEach((name, age) -> LOG.debug(name + " is " + age + " years old"));
     }
 
     @Test

core-java/src/test/java/com/baeldung/java/collections/ConcurrentModificationExceptionTest.java

@@ -6,9 +6,10 @@ import java.util.*;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import static java.util.Arrays.asList;
-import static org.testng.Assert.assertEquals;
+import static org.junit.Assert.assertEquals;
 
 public class ConcurrentModificationExceptionTest {
+
     @Test
     public void changingContentWithSetDoesNotThrowConcurrentModificationException() throws Exception {
         ArrayList<Object> array = new ArrayList<>(asList(0, "one", 2, "three"));

core-java/src/test/java/com/baeldung/java/concurrentmap/ConcurrentNavigableMapManualTests.java

@@ -8,7 +8,9 @@ import java.util.TreeMap;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import static org.testng.Assert.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertTrue;
 
 public class ConcurrentNavigableMapManualTests {
 

core-java/src/test/java/com/baeldung/java/map/MapTest.java

@@ -1,24 +1,18 @@
 package com.baeldung.java.map;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
-
-import java.util.Collection;
-import java.util.Comparator;
-import java.util.ConcurrentModificationException;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.Set;
-import java.util.TreeMap;
-
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.*;
+import java.util.Map.Entry;
+
+import static org.junit.Assert.*;
 
 public class MapTest {
+    private static final Logger LOG = LoggerFactory.getLogger(MapTest.class);
+
+    
     @Test
     public void givenHashMap_whenRetrievesKeyset_thenCorrect() {
         Map<String, String> map = new HashMap<>();
@@ -208,22 +202,22 @@ public class MapTest {
         MyKey k2 = new MyKey(2, "secondKey");
         MyKey k3 = new MyKey(2, "thirdKey");
 
-        System.out.println("storing value for k1");
+        LOG.debug("storing value for k1");
         map.put(k1, "firstValue");
 
-        System.out.println("storing value for k2");
+        LOG.debug("storing value for k2");
         map.put(k2, "secondValue");
 
-        System.out.println("storing value for k3");
+        LOG.debug("storing value for k3");
         map.put(k3, "thirdValue");
 
-        System.out.println("retrieving value for k1");
+        LOG.debug("retrieving value for k1");
         String v1 = map.get(k1);
 
-        System.out.println("retrieving value for k2");
+        LOG.debug("retrieving value for k2");
         String v2 = map.get(k2);
 
-        System.out.println("retrieving value for k3");
+        LOG.debug("retrieving value for k3");
         String v3 = map.get(k3);
 
         assertEquals("firstValue", v1);

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoClient.java

@@ -1,5 +1,8 @@
 package com.baeldung.java.nio2.async;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
@@ -10,6 +13,8 @@ import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 
 public class AsyncEchoClient {
+    private static final Logger LOG = LoggerFactory.getLogger(AsyncEchoClient.class);
+
     private AsynchronousSocketChannel client;
     private Future<Void> future;
     private static AsyncEchoClient instance;
@@ -75,11 +80,11 @@ public class AsyncEchoClient {
         client.start();
         BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
         String line;
-        System.out.println("Message to server:");
+        LOG.debug("Message to server:");
         while ((line = br.readLine()) != null) {
             String response = client.sendMessage(line);
-            System.out.println("response from server: " + response);
+            LOG.debug("response from server: " + response);
-            System.out.println("Message to server:");
+            LOG.debug("Message to server:");
         }
     }
 

core-java/src/test/java/com/baeldung/java/nio2/attributes/BasicAttribsTest.java

@@ -2,6 +2,8 @@ package com.baeldung.java.nio2.attributes;
 
 import org.junit.BeforeClass;
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -15,6 +17,10 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 public class BasicAttribsTest {
+
+    private static final Logger LOG = LoggerFactory.getLogger(BasicAttribsTest.class);
+
+
     private static final String HOME = System.getProperty("user.home");
     private static BasicFileAttributes basicAttribs;
 
@@ -31,9 +37,9 @@ public class BasicAttribsTest {
         FileTime modified = basicAttribs.lastModifiedTime();
         FileTime accessed = basicAttribs.lastAccessTime();
 
-        System.out.println("Created: " + created);
+        LOG.debug("Created: " + created);
-        System.out.println("Modified: " + modified);
+        LOG.debug("Modified: " + modified);
-        System.out.println("Accessed: " + accessed);
+        LOG.debug("Accessed: " + accessed);
 
     }
 

core-java/src/test/java/com/baeldung/java/set/SetTest.java

@@ -1,6 +1,8 @@
 package com.baeldung.java.set;
 
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.*;
 
@@ -9,6 +11,8 @@ import static org.junit.Assert.assertTrue;
 
 public class SetTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(SetTest.class);
+
     @Test
     public void givenTreeSet_whenRetrievesObjects_thenNaturalOrder() {
         Set<String> set = new TreeSet<>();
@@ -88,7 +92,7 @@ public class SetTest {
         task.run();
         long endTime = System.nanoTime();
         long executionTime = endTime - startTime;
-        System.out.println(executionTime);
+        LOG.debug(String.valueOf(executionTime));
         return executionTime;
     }
 }

core-java/src/test/java/com/baeldung/java8/Java8ForEachTest.java

@@ -1,13 +1,17 @@
 package com.baeldung.java8;
 
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Consumer;
 
-import org.junit.Test;
-
 public class Java8ForEachTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(Java8ForEachTest.class);
+
     @Test
     public void compareForEachMethods_thenPrintResults() {
 
@@ -19,33 +23,33 @@ public class Java8ForEachTest {
         names.add("Ellen");
 
         // Java 5 - for-loop
-        System.out.println("--- Enhanced for-loop ---");
+        LOG.debug("--- Enhanced for-loop ---");
         for (String name : names) {
-            System.out.println(name);
+            LOG.debug(name);
         }
 
         // Java 8 - forEach
-        System.out.println("--- forEach method ---");
+        LOG.debug("--- forEach method ---");
-        names.forEach(name -> System.out.println(name));
+        names.forEach(name -> LOG.debug(name));
 
         // Anonymous inner class that implements Consumer interface
-        System.out.println("--- Anonymous inner class ---");
+        LOG.debug("--- Anonymous inner class ---");
         names.forEach(new Consumer<String>() {
             public void accept(String name) {
-                System.out.println(name);
+                LOG.debug(name);
             }
         });
 
         // Create a Consumer implementation to then use in a forEach method
         Consumer<String> consumerNames = name -> {
-            System.out.println(name);
+            LOG.debug(name);
         };
-        System.out.println("--- Implementation of Consumer interface ---");
+        LOG.debug("--- Implementation of Consumer interface ---");
         names.forEach(consumerNames);
 
         // Print elements using a Method Reference
-        System.out.println("--- Method Reference ---");
+        LOG.debug("--- Method Reference ---");
-        names.forEach(System.out::println);
+        names.forEach(LOG::debug);
 
     }
 

core-java/src/test/java/com/baeldung/java8/JavaTryWithResourcesLongRunningUnitTest.java

@@ -2,6 +2,8 @@ package com.baeldung.java8;
 
 import org.junit.Assert;
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.PrintWriter;
 import java.io.StringWriter;
@@ -10,6 +12,9 @@ import java.util.Scanner;
 
 public class JavaTryWithResourcesLongRunningUnitTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(JavaTryWithResourcesLongRunningUnitTest.class);
+
+
     private static final String TEST_STRING_HELLO_WORLD = "Hello World";
     private Date resource1Date, resource2Date;
 
@@ -52,32 +57,32 @@ public class JavaTryWithResourcesLongRunningUnitTest {
 
     class AutoCloseableResourcesFirst implements AutoCloseable {
         public AutoCloseableResourcesFirst() {
-            System.out.println("Constructor -> AutoCloseableResources_First");
+            LOG.debug("Constructor -> AutoCloseableResources_First");
         }
 
         public void doSomething() {
-            System.out.println("Something -> AutoCloseableResources_First");
+            LOG.debug("Something -> AutoCloseableResources_First");
         }
 
         @Override
         public void close() throws Exception {
-            System.out.println("Closed AutoCloseableResources_First");
+            LOG.debug("Closed AutoCloseableResources_First");
             resource1Date = new Date();
         }
     }
 
     class AutoCloseableResourcesSecond implements AutoCloseable {
         public AutoCloseableResourcesSecond() {
-            System.out.println("Constructor -> AutoCloseableResources_Second");
+            LOG.debug("Constructor -> AutoCloseableResources_Second");
         }
 
         public void doSomething() {
-            System.out.println("Something -> AutoCloseableResources_Second");
+            LOG.debug("Something -> AutoCloseableResources_Second");
         }
 
         @Override
         public void close() throws Exception {
-            System.out.println("Closed AutoCloseableResources_Second");
+            LOG.debug("Closed AutoCloseableResources_Second");
             resource2Date = new Date();
             Thread.sleep(10000);
         }

core-java/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaExceptionWrappersTest.java

@@ -2,6 +2,8 @@ package com.baeldung.java8.lambda.exceptions;
 
 import org.junit.Before;
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.util.Arrays;
@@ -11,6 +13,9 @@ import static com.baeldung.java8.lambda.exceptions.LambdaExceptionWrappers.*;
 
 public class LambdaExceptionWrappersTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(LambdaExceptionWrappersTest.class);
+
+
     private List<Integer> integers;
 
     @Before
@@ -20,12 +25,12 @@ public class LambdaExceptionWrappersTest {
 
     @Test
     public void whenNoExceptionFromLambdaWrapper_thenSuccess() {
-        integers.forEach(lambdaWrapper(i -> System.out.println(50 / i)));
+        integers.forEach(lambdaWrapper(i -> LOG.debug("{}", 50 / i)));
     }
 
     @Test
     public void whenNoExceptionFromConsumerWrapper_thenSuccess() {
-        integers.forEach(consumerWrapper(i -> System.out.println(50 / i), ArithmeticException.class));
+        integers.forEach(consumerWrapper(i -> LOG.debug("{}", 50 / i), ArithmeticException.class));
     }
 
     @Test(expected = RuntimeException.class)

core-java/src/test/java/com/baeldung/java8/optional/OptionalTest.java

@@ -3,6 +3,8 @@ package com.baeldung.java8.optional;
 import com.baeldung.optional.Modem;
 import com.baeldung.optional.Person;
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.Arrays;
 import java.util.List;
@@ -12,6 +14,10 @@ import java.util.Optional;
 import static org.junit.Assert.*;
 
 public class OptionalTest {
+
+    private static final Logger LOG = LoggerFactory.getLogger(OptionalTest.class);
+
+    
     // creating Optional
     @Test
     public void whenCreatesEmptyOptional_thenCorrect() {
@@ -66,7 +72,7 @@ public class OptionalTest {
     @Test
     public void givenOptional_whenIfPresentWorks_thenCorrect() {
         Optional<String> opt = Optional.of("baeldung");
-        opt.ifPresent(name -> System.out.println(name.length()));
+        opt.ifPresent(name -> LOG.debug("{}", name.length()));
     }
 
     // returning Value With get()
@@ -200,11 +206,11 @@ public class OptionalTest {
     @Test
     public void whenOrElseGetAndOrElseOverlap_thenCorrect() {
         String text = null;
-        System.out.println("Using orElseGet:");
+        LOG.debug("Using orElseGet:");
         String defaultText = Optional.ofNullable(text).orElseGet(this::getMyDefault);
         assertEquals("Default Value", defaultText);
 
-        System.out.println("Using orElse:");
+        LOG.debug("Using orElse:");
         defaultText = Optional.ofNullable(text).orElse(getMyDefault());
         assertEquals("Default Value", defaultText);
     }
@@ -212,11 +218,11 @@ public class OptionalTest {
     @Test
     public void whenOrElseGetAndOrElseDiffer_thenCorrect() {
         String text = "Text present";
-        System.out.println("Using orElseGet:");
+        LOG.debug("Using orElseGet:");
         String defaultText = Optional.ofNullable(text).orElseGet(this::getMyDefault);
         assertEquals("Text present", defaultText);
 
-        System.out.println("Using orElse:");
+        LOG.debug("Using orElse:");
         defaultText = Optional.ofNullable(text).orElse(getMyDefault());
         assertEquals("Text present", defaultText);
     }
@@ -229,7 +235,7 @@ public class OptionalTest {
     }
 
     public String getMyDefault() {
-        System.out.println("Getting default value...");
+        LOG.debug("Getting default value...");
         return "Default Value";
     }
 }

core-java/src/test/java/com/baeldung/synchronousqueue/SynchronousQueueTest.java

@@ -3,6 +3,8 @@ package com.baeldung.synchronousqueue;
 import org.junit.FixMethodOrder;
 import org.junit.Test;
 import org.junit.runners.MethodSorters;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -12,6 +14,9 @@ import static junit.framework.TestCase.assertEquals;
 @FixMethodOrder(MethodSorters.NAME_ASCENDING)
 public class SynchronousQueueTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(SynchronousQueueTest.class);
+
+
     @Test
     public void givenTwoThreads_whenWantToExchangeUsingLockGuardedVariable_thenItSucceed() throws InterruptedException {
         //given
@@ -21,7 +26,7 @@ public class SynchronousQueueTest {
 
         Runnable producer = () -> {
             Integer producedElement = ThreadLocalRandom.current().nextInt();
-            System.out.println("Saving an element: " + producedElement + " to the exchange point");
+            LOG.debug("Saving an element: " + producedElement + " to the exchange point");
             sharedState.set(producedElement);
             countDownLatch.countDown();
         };
@@ -30,7 +35,7 @@ public class SynchronousQueueTest {
             try {
                 countDownLatch.await();
                 Integer consumedElement = sharedState.get();
-                System.out.println("consumed an element: " + consumedElement + " from the exchange point");
+                LOG.debug("consumed an element: " + consumedElement + " from the exchange point");
             } catch (InterruptedException ex) {
                 ex.printStackTrace();
             }
@@ -55,7 +60,7 @@ public class SynchronousQueueTest {
         Runnable producer = () -> {
             Integer producedElement = ThreadLocalRandom.current().nextInt();
             try {
-                System.out.println("Saving an element: " + producedElement + " to the exchange point");
+                LOG.debug("Saving an element: " + producedElement + " to the exchange point");
                 queue.put(producedElement);
             } catch (InterruptedException ex) {
                 ex.printStackTrace();
@@ -65,7 +70,7 @@ public class SynchronousQueueTest {
         Runnable consumer = () -> {
             try {
                 Integer consumedElement = queue.take();
-                System.out.println("consumed an element: " + consumedElement + " from the exchange point");
+                LOG.debug("consumed an element: " + consumedElement + " from the exchange point");
             } catch (InterruptedException ex) {
                 ex.printStackTrace();
             }

core-java/src/test/java/com/baeldung/threadpool/CoreThreadPoolIntegrationTest.java

@@ -1,24 +1,19 @@
 package com.baeldung.threadpool;
 
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
 import static org.junit.Assert.assertEquals;
 
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Executor;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ForkJoinPool;
-import java.util.concurrent.Future;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.ScheduledFuture;
-import java.util.concurrent.ThreadPoolExecutor;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicInteger;
-
-import org.junit.Test;
-
 public class CoreThreadPoolIntegrationTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(CoreThreadPoolIntegrationTest.class);
+
+
     @Test(timeout = 1000)
     public void whenCallingExecuteWithRunnable_thenRunnableIsExecuted() throws InterruptedException {
 
@@ -26,7 +21,7 @@ public class CoreThreadPoolIntegrationTest {
 
         Executor executor = Executors.newSingleThreadExecutor();
         executor.execute(() -> {
-            System.out.println("Hello World");
+            LOG.debug("Hello World");
             lock.countDown();
         });
 
@@ -115,7 +110,7 @@ public class CoreThreadPoolIntegrationTest {
 
         ScheduledExecutorService executor = Executors.newScheduledThreadPool(5);
         executor.schedule(() -> {
-            System.out.println("Hello World");
+            LOG.debug("Hello World");
             lock.countDown();
         }, 500, TimeUnit.MILLISECONDS);
 
@@ -130,7 +125,7 @@ public class CoreThreadPoolIntegrationTest {
 
         ScheduledExecutorService executor = Executors.newScheduledThreadPool(5);
         ScheduledFuture<?> future = executor.scheduleAtFixedRate(() -> {
-            System.out.println("Hello World");
+            LOG.debug("Hello World");
             lock.countDown();
         }, 500, 100, TimeUnit.MILLISECONDS);
 

core-java/src/test/java/org/baeldung/core/exceptions/FileNotFoundExceptionUnitTest.java

@@ -1,15 +1,10 @@
 package org.baeldung.core.exceptions;
 
-import java.io.BufferedReader;
+import org.junit.Test;
-import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.FileReader;
-import java.io.IOException;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import org.junit.Test;
+import java.io.*;
 
 public class FileNotFoundExceptionUnitTest {
 
@@ -22,7 +17,7 @@ public class FileNotFoundExceptionUnitTest {
         try {
             readFailingFile();
         } catch (FileNotFoundException ex) {
-            throw new BusinessException("BusinessException: necessary file was not present.", ex);
+            throw new BusinessException("BusinessException: necessary file was not present.");
         }
     }
 
@@ -35,7 +30,7 @@ public class FileNotFoundExceptionUnitTest {
                 new File(fileName).createNewFile();
                 readFailingFile();
             } catch (IOException ioe) {
-                throw new RuntimeException("BusinessException: even creation is not possible.", ioe);
+                throw new RuntimeException("BusinessException: even creation is not possible.");
             }
         }
     }
@@ -45,7 +40,7 @@ public class FileNotFoundExceptionUnitTest {
         try {
             readFailingFile();
         } catch (FileNotFoundException ex) {
-            LOG.error("Optional file " + fileName + " was not found.", ex);
+            LOG.error("Optional file " + fileName + " was not found.");
         }
     }
 
@@ -56,8 +51,8 @@ public class FileNotFoundExceptionUnitTest {
     }
 
     private class BusinessException extends RuntimeException {
-        BusinessException(String string, FileNotFoundException ex) {
+        BusinessException(String string) {
-            super(string, ex);
+            super(string);
         }
     }
 }

core-java/src/test/java/org/baeldung/java/JavaRandomUnitTest.java

@@ -3,26 +3,31 @@ package org.baeldung.java;
 import org.apache.commons.lang3.RandomStringUtils;
 import org.apache.commons.math3.random.RandomDataGenerator;
 import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.nio.charset.Charset;
 import java.util.Random;
 
 public class JavaRandomUnitTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(JavaRandomUnitTest.class);
+
+
     // tests - random long
 
     @Test
     public void givenUsingPlainJava_whenGeneratingRandomLongUnbounded_thenCorrect() {
         final long generatedLong = new Random().nextLong();
 
-        System.out.println(generatedLong);
+        LOG.debug("{}", generatedLong);
     }
 
     @Test
     public void givenUsingApacheCommons_whenGeneratingRandomLongUnbounded_thenCorrect() {
         final long generatedLong = new RandomDataGenerator().getRandomGenerator().nextLong();
 
-        System.out.println(generatedLong);
+        LOG.debug("{}", generatedLong);
     }
 
     @Test
@@ -31,7 +36,7 @@ public class JavaRandomUnitTest {
         final long rightLimit = 10L;
         final long generatedLong = leftLimit + (long) (Math.random() * (rightLimit - leftLimit));
 
-        System.out.println(generatedLong);
+        LOG.debug("{}", generatedLong);
     }
 
     @Test
@@ -40,7 +45,7 @@ public class JavaRandomUnitTest {
         final long rightLimit = 100L;
         final long generatedLong = new RandomDataGenerator().nextLong(leftLimit, rightLimit);
 
-        System.out.println(generatedLong);
+        LOG.debug("{}", generatedLong);
     }
 
     // tests - random int
@@ -49,7 +54,7 @@ public class JavaRandomUnitTest {
     public void givenUsingPlainJava_whenGeneratingRandomIntegerUnbounded_thenCorrect() {
         final int generatedInteger = new Random().nextInt();
 
-        System.out.println(generatedInteger);
+        LOG.debug("{}", generatedInteger);
     }
 
     @Test
@@ -58,14 +63,14 @@ public class JavaRandomUnitTest {
         final int rightLimit = 10;
         final int generatedInteger = leftLimit + (int) (new Random().nextFloat() * (rightLimit - leftLimit));
 
-        System.out.println(generatedInteger);
+        LOG.debug("{}", generatedInteger);
     }
 
     @Test
     public void givenUsingApache_whenGeneratingRandomIntegerUnbounded_thenCorrect() {
         final Integer generatedInteger = new RandomDataGenerator().getRandomGenerator().nextInt();
 
-        System.out.println(generatedInteger);
+        LOG.debug("{}", generatedInteger);
     }
 
     @Test
@@ -74,7 +79,7 @@ public class JavaRandomUnitTest {
         final int rightLimit = 10;
         final int generatedInteger = new RandomDataGenerator().nextInt(leftLimit, rightLimit);
 
-        System.out.println(generatedInteger);
+        LOG.debug("{}", generatedInteger);
     }
 
     // tests - random float
@@ -83,14 +88,14 @@ public class JavaRandomUnitTest {
     public void givenUsingPlainJava_whenGeneratingRandomFloatUnbouned_thenCorrect() {
         final float generatedFloat = new Random().nextFloat();
 
-        System.out.println(generatedFloat);
+        LOG.debug("{}", generatedFloat);
     }
 
     @Test
     public void givenUsingApache_whenGeneratingRandomFloatUnbounded_thenCorrect() {
         final float generatedFloat = new RandomDataGenerator().getRandomGenerator().nextFloat();
 
-        System.out.println(generatedFloat);
+        LOG.debug("{}", generatedFloat);
     }
 
     @Test
@@ -99,7 +104,7 @@ public class JavaRandomUnitTest {
         final float rightLimit = 10F;
         final float generatedFloat = leftLimit + new Random().nextFloat() * (rightLimit - leftLimit);
 
-        System.out.println(generatedFloat);
+        LOG.debug("{}", generatedFloat);
     }
 
     @Test
@@ -109,7 +114,7 @@ public class JavaRandomUnitTest {
         final float randomFloat = new RandomDataGenerator().getRandomGenerator().nextFloat();
         final float generatedFloat = leftLimit + randomFloat * (rightLimit - leftLimit);
 
-        System.out.println(generatedFloat);
+        LOG.debug("{}", generatedFloat);
     }
 
     // tests - random double
@@ -118,14 +123,14 @@ public class JavaRandomUnitTest {
     public void givenUsingPlainJava_whenGeneratingRandomDoubleUnbounded_thenCorrect() {
         final double generatedDouble = Math.random();
 
-        System.out.println(generatedDouble);
+        LOG.debug("{}", generatedDouble);
     }
 
     @Test
     public void givenUsingApache_whenGeneratingRandomDoubleUnbounded_thenCorrect() {
         final double generatedDouble = new RandomDataGenerator().getRandomGenerator().nextDouble();
 
-        System.out.println(generatedDouble);
+        LOG.debug("{}", generatedDouble);
     }
 
     @Test
@@ -134,7 +139,7 @@ public class JavaRandomUnitTest {
         final double rightLimit = 10D;
         final double generatedDouble = leftLimit + new Random().nextDouble() * (rightLimit - leftLimit);
 
-        System.out.println(generatedDouble);
+        LOG.debug("{}", generatedDouble);
     }
 
     @Test
@@ -143,7 +148,7 @@ public class JavaRandomUnitTest {
         final double rightLimit = 100D;
         final double generatedDouble = new RandomDataGenerator().nextUniform(leftLimit, rightLimit);
 
-        System.out.println(generatedDouble);
+        LOG.debug("{}", generatedDouble);
     }
 
     // tests - random String
@@ -154,7 +159,7 @@ public class JavaRandomUnitTest {
         new Random().nextBytes(array);
         final String generatedString = new String(array, Charset.forName("UTF-8"));
 
-        System.out.println(generatedString);
+        LOG.debug(generatedString);
     }
 
     @Test
@@ -169,28 +174,28 @@ public class JavaRandomUnitTest {
         }
         final String generatedString = buffer.toString();
 
-        System.out.println(generatedString);
+        LOG.debug(generatedString);
     }
 
     @Test
     public void givenUsingApache_whenGeneratingRandomString_thenCorrect() {
         final String generatedString = RandomStringUtils.random(10);
 
-        System.out.println(generatedString);
+        LOG.debug(generatedString);
     }
 
     @Test
     public void givenUsingApache_whenGeneratingRandomAlphabeticString_thenCorrect() {
         final String generatedString = RandomStringUtils.randomAlphabetic(10);
 
-        System.out.println(generatedString);
+        LOG.debug(generatedString);
     }
 
     @Test
     public void givenUsingApache_whenGeneratingRandomAlphanumericString_thenCorrect() {
         final String generatedString = RandomStringUtils.randomAlphanumeric(10);
 
-        System.out.println(generatedString);
+        LOG.debug(generatedString);
     }
 
     @Test
@@ -200,7 +205,7 @@ public class JavaRandomUnitTest {
         final boolean useNumbers = false;
         final String generatedString = RandomStringUtils.random(length, useLetters, useNumbers);
 
-        System.out.println(generatedString);
+        LOG.debug(generatedString);
     }
 
 }

core-java/src/test/java/org/baeldung/java/JavaTimerLongRunningUnitTest.java

@@ -1,5 +1,9 @@
 package org.baeldung.java;
 
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.Date;
 import java.util.Timer;
 import java.util.TimerTask;
@@ -7,10 +11,11 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
-import org.junit.Test;
-
 public class JavaTimerLongRunningUnitTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(JavaTimerLongRunningUnitTest.class);
+
+
     // tests
 
     @Test
@@ -18,7 +23,7 @@ public class JavaTimerLongRunningUnitTest {
         final TimerTask timerTask = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Task performed on: " + new Date() + "\n" + "Thread's name: " + Thread.currentThread().getName());
+                LOG.debug("Task performed on: " + new Date() + "\n" + "Thread's name: " + Thread.currentThread().getName());
             }
         };
         final Timer timer = new Timer("Timer");
@@ -35,7 +40,7 @@ public class JavaTimerLongRunningUnitTest {
         final TimerTask repeatedTask = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Task performed on " + new Date());
+                LOG.debug("Task performed on " + new Date());
             }
         };
         final Timer timer = new Timer("Timer");
@@ -53,7 +58,7 @@ public class JavaTimerLongRunningUnitTest {
         final TimerTask repeatedTask = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Task performed on " + new Date());
+                LOG.debug("Task performed on " + new Date());
             }
         };
         final Timer timer = new Timer("Timer");
@@ -71,7 +76,7 @@ public class JavaTimerLongRunningUnitTest {
         final TimerTask task = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Task performed on " + new Date());
+                LOG.debug("Task performed on " + new Date());
                 cancel();
             }
         };
@@ -89,7 +94,7 @@ public class JavaTimerLongRunningUnitTest {
         final TimerTask task = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Task performed on " + new Date());
+                LOG.debug("Task performed on " + new Date());
             }
         };
         final Timer timer = new Timer("Timer");
@@ -104,7 +109,7 @@ public class JavaTimerLongRunningUnitTest {
         final TimerTask task = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Task performed on " + new Date());
+                LOG.debug("Task performed on " + new Date());
             }
         };
         final Timer timer = new Timer("Timer");
@@ -120,7 +125,7 @@ public class JavaTimerLongRunningUnitTest {
         final TimerTask repeatedTask = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Task performed on " + new Date());
+                LOG.debug("Task performed on " + new Date());
             }
         };
         final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();

core-java/src/test/java/org/baeldung/java/collections/CoreJavaCollectionsUnitTest.java

@@ -1,24 +1,28 @@
 package org.baeldung.java.collections;
 
+import com.google.common.collect.ImmutableList;
+import org.apache.commons.collections4.ListUtils;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
-import org.apache.commons.collections4.ListUtils;
-import org.junit.Test;
-
-import com.google.common.collect.ImmutableList;
-
 public class CoreJavaCollectionsUnitTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(CoreJavaCollectionsUnitTest.class);
+
+
     // tests -
 
     @Test
     public final void givenUsingTheJdk_whenArrayListIsSynchronized_thenCorrect() {
         final List<String> list = new ArrayList<String>(Arrays.asList("one", "two", "three"));
         final List<String> synchronizedList = Collections.synchronizedList(list);
-        System.out.println("Synchronized List is: " + synchronizedList);
+        LOG.debug("Synchronized List is: " + synchronizedList);
     }
 
     @Test(expected = UnsupportedOperationException.class)

core-java/src/test/java/org/baeldung/java/io/JavaReadFromFileUnitTest.java

@@ -1,18 +1,10 @@
 package org.baeldung.java.io;
 
-import static org.junit.Assert.assertEquals;
+import org.junit.Test;
-import static org.junit.Assert.assertTrue;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-import java.io.BufferedReader;
+import java.io.*;
-import java.io.DataInputStream;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileReader;
-import java.io.IOException;
-import java.io.InputStreamReader;
-import java.io.RandomAccessFile;
-import java.io.SequenceInputStream;
-import java.io.StreamTokenizer;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.charset.Charset;
@@ -21,10 +13,14 @@ import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Scanner;
 
-import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 public class JavaReadFromFileUnitTest {
 
+
+    private static final Logger LOG = LoggerFactory.getLogger(JavaReadFromFileUnitTest.class);
+
     @Test
     public void whenReadWithBufferedReader_thenCorrect() throws IOException {
         final String expected_value = "Hello world";
@@ -115,7 +111,7 @@ public class JavaReadFromFileUnitTest {
         final BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("src/test/resources/test_read7.in"), "UTF-8"));
         final String currentLine = reader.readLine();
         reader.close();
-        System.out.println(currentLine);
+        LOG.debug(currentLine);
         assertEquals(expected_value, currentLine);
     }
 

core-java/src/test/java/org/baeldung/java/lists/ListTestNgUnitTest.java

@@ -1,11 +1,12 @@
 package org.baeldung.java.lists;
 
-import org.testng.Assert;
+import org.junit.Test;
-import org.testng.annotations.Test;
 
 import java.util.Arrays;
 import java.util.List;
 
+import static org.junit.Assert.*;
+
 public class ListTestNgUnitTest {
 
     private final List<String> list1 = Arrays.asList("1", "2", "3", "4");
@@ -14,8 +15,8 @@ public class ListTestNgUnitTest {
 
     @Test
     public void whenTestingForEquality_ShouldBeEqual() throws Exception {
-        Assert.assertEquals(list1, list2);
+        assertEquals(list1, list2);
-        Assert.assertNotSame(list1, list2);
+        assertNotSame(list1, list2);
-        Assert.assertNotEquals(list1, list3);
+        assertNotEquals(list1, list3);
     }
 }

core-java/src/test/java/org/baeldung/java/sandbox/SandboxJavaManualTest.java

@@ -1,25 +1,30 @@
 package org.baeldung.java.sandbox;
 
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.Date;
 import java.util.Timer;
 import java.util.TimerTask;
 
-import org.junit.Test;
-
 public class SandboxJavaManualTest {
 
+
+    private static final Logger LOG = LoggerFactory.getLogger(SandboxJavaManualTest.class);
+
     @Test
     public void givenUsingTimer_whenSchedulingTimerTaskOnce_thenCorrect() throws InterruptedException {
         final TimerTask timerTask = new TimerTask() {
             @Override
             public void run() {
-                System.out.println("Time when was task performed" + new Date());
+                LOG.debug("Time when was task performed" + new Date());
-                System.out.println("Thread's name: " + Thread.currentThread().getName());
+                LOG.debug("Thread's name: " + Thread.currentThread().getName());
             }
         };
         final Timer timer = new Timer("Thread's name");
-        System.out.println("Current time:" + new Date());
+        LOG.debug("Current time:" + new Date());
-        System.out.println("Thread's name: " + Thread.currentThread().getName());
+        LOG.debug("Thread's name: " + Thread.currentThread().getName());
         final long delay = 2L * 1000L;
         timer.schedule(timerTask, delay);
         Thread.sleep(delay);
@@ -33,16 +38,16 @@ public class SandboxJavaManualTest {
             @Override
             public void run() {
                 count++;
-                System.out.println("Time when task was performed: " + new Date());
+                LOG.debug("Time when task was performed: " + new Date());
-                System.out.println("Thread's name: " + Thread.currentThread().getName());
+                LOG.debug("Thread's name: " + Thread.currentThread().getName());
                 if (count >= 5) {
                     cancel();
                 }
             }
         };
         final Timer timer = new Timer("Timer thread");
-        System.out.println("Current time: " + new Date());
+        LOG.debug("Current time: " + new Date());
-        System.out.println("Thread's name: " + Thread.currentThread().getName());
+        LOG.debug("Thread's name: " + Thread.currentThread().getName());
         final long delay = 2L * 1000L;
         final long period = 1L * 1000L;
         timer.scheduleAtFixedRate(repeatedTask, delay, period);
@@ -62,8 +67,8 @@ public class SandboxJavaManualTest {
             @Override
             public void run() {
                 timesRunned++;
-                System.out.println("Task performed on: " + new Date());
+                LOG.debug("Task performed on: " + new Date());
-                System.out.println("Thread's name: " + Thread.currentThread().getName());
+                LOG.debug("Thread's name: " + Thread.currentThread().getName());
                 if (timesRunned >= timesToRun) {
                     cancel();
                 }
@@ -72,10 +77,10 @@ public class SandboxJavaManualTest {
         final MyTask repeatedTask = new MyTask();
         repeatedTask.setTimesToRun(5);
         final long delay = 2L * 1000L;
-        final long period = 1L * 1000L;
+        final long period = 1000L;
         final Timer timer = new Timer("Timer");
-        System.out.println("Current time: " + new Date());
+        LOG.debug("Current time: " + new Date());
-        System.out.println("Thread's name: " + Thread.currentThread().getName());
+        LOG.debug("Thread's name: " + Thread.currentThread().getName());
         timer.scheduleAtFixedRate(repeatedTask, delay, period);
         Thread.sleep(delay + period * repeatedTask.timesToRun);
     }

cucumber/pom.xml

@@ -77,14 +77,14 @@
           <target>${java.target.version}</target>
         </configuration>
       </plugin>
+
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
-        <version>${surefire.plugin.version}</version>
         <configuration>
-          <includes>
+          <excludes>
-            <include>**/CalculatorTest.java</include>
+            <exclude>**/*IntegrationTest.java</exclude>
-          </includes>
+          </excludes>
         </configuration>
       </plugin>
     </plugins>

cucumber/src/test/java/com/baeldung/cucumber/calculator/CalculatorIntegrationTest.java

@@ -11,5 +11,5 @@ import cucumber.api.junit.Cucumber;
     , plugin = { "pretty", "json:target/reports/json/calculator.json" }
     , glue = {"com.baeldung.cucumber.calculator"}
 )
-public class CalculatorTest {
+public class CalculatorIntegrationTest {
 }

pom.xml

@@ -52,6 +52,7 @@
         <module>handling-spring-static-resources</module>
         <module>hazelcast</module>
         <module>hbase</module>
+        <module>hibernate5</module>
         <module>httpclient</module>
         <module>hystrix</module>
 
@@ -200,7 +201,7 @@
 
         <module>video-tutorials</module>
 
-        <module>wicket</module>
+        <!--<module>wicket</module>-->
 
         <module>xml</module>
         <module>xmlunit2</module>
@@ -225,8 +226,6 @@
                 <version>1.6.0</version>
                 <configuration>
                     <executable>maven</executable>
-        <module>hibernate5</module>
-
                 </configuration>
             </plugin>
             <plugin>

wicket/pom.xml

@@ -4,10 +4,10 @@
 
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung.wicket.examples</groupId>
-    <artifactId>wicket-intro</artifactId>
+    <artifactId>wicket</artifactId>
     <packaging>war</packaging>
     <version>1.0-SNAPSHOT</version>
-    <name>WicketIntro</name>
+    <name>Wicket</name>
     <properties>
         <wicket.version>7.5.0</wicket.version>
         <jetty9.version>9.2.13.v20150730</jetty9.version>
@@ -100,6 +100,16 @@
                 <artifactId>jetty-maven-plugin</artifactId>
                 <version>${jetty9.version}</version>
             </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <configuration>
+                    <excludes>
+                        <exclude>**/*IntegrationTest.java</exclude>
+                    </excludes>
+                </configuration>
+            </plugin>
         </plugins>
     </build>
 </project>