BAEL-1309 Append Data to a File with Java (#3054)

* Evaluation article: Different Types of Bean Injection in Spring

* added tests & changed configuration to Java-based config

* removed xml config files

* rename unit tests

* BAEL-972 - Apache Commons Text

* remove code from evaluation article

* remove code from evaluation article

* BAEL-972 - Apache Commons Text - added another example

* BAEL-972 - Apache Commons Text - just indentation

* BAEL-994 - TemporalAdjuster in Java

* BAEL-994 - TemporalAdjuster in Java

* BAEL-994 - TemporalAdjuster in Java

* BAEL-994 - TemporalAdjuster in Java

* BAEL-994 - TemporalAdjuster in Java - fix problems

* BAEL-1033 Introduction to StreamUtils

* BAEL-1033 Introduction to StreamUtils

* BAEL-1033 Introduction to StreamUtils

* fix formatting

* BAEL-1033 minor refactor

* BAEL-1035 Introduction to Eclipse Collections

* format

* BAEL-1035 Introduction to Eclipse Collections

* BAEL-1035 Introduction to Eclipse Collections

* BAEL-1035 Introduction to Eclipse Collections

* cleanup

* cleanup

* BAEL-1109 Introduction to JCache

* BAEL-1109 Introduction to JCache

* remove unneeded property in pom.xml

* fix formatting

* close cache instances properly

* remove latest commit

* BAEL-1057 Introduction to rxjava-jdbc

* refactor rxjava-jdbc

* Refactor rxjava-jdbc

* Refactoring rxjava-jdbc

* BAEL-1171 java.lang.String API

* refactor rxjava-jdbc

* refactor String

* String API - move multiple classes into a single class

* move class into test package

* BAEL-1171 String.lang.String API

* BAEL-1171 java.lang.String API

* BAEL-1250 Initializing Arrays in Java

* BAEL-1250 Initializing Arrays in Java

* BAEL-1250 Initializing Arrays in Java

* small fix

* BAEL-1171 java.lang.String API

* BAEL-1263 Daemon Threads in Java

* merge with fork

* BAEL-1263 Daemon Threads in Java

* fix compilation error

* BAEL-1309 Append Data to a File with Java

* fix build fails

* fix test error

* fix build failures

* cleanup

* fix Sneaky Runnable test

* revert sneaky runnable fix attempt

* fix test failure

* fix test failure

* fix all test failures

* fix test failure

* fix test failures

* Nested Classes in Java

core-java-concurrency/src/main/java/com/baeldung/concurrent/daemon/NewThread.java

@@ -3,7 +3,6 @@ package com.baeldung.concurrent.daemon;
 public class NewThread extends Thread {
 
     public void run() {
-    	
     	long startTime = System.currentTimeMillis();
         while (true) {
             for (int i = 0; i < 10; i++) {

core-java/src/main/java/com/baeldung/nestedclass/Enclosing.java

@@ -0,0 +1,11 @@
+package com.baeldung.nestedclass;
+
+public class Enclosing {
+
+    public static class Nested {
+
+        public void test() {
+            System.out.println("Calling test...");
+        }
+    }
+}

core-java/src/main/java/com/baeldung/nestedclass/NewEnclosing.java

@@ -0,0 +1,15 @@
+package com.baeldung.nestedclass;
+
+public class NewEnclosing {
+
+    void run() {
+        class Local {
+
+            void run() {
+                System.out.println("Welcome to Baeldung!");
+            }
+        }
+        Local local = new Local();
+        local.run();
+    }
+}

core-java/src/main/java/com/baeldung/nestedclass/Outer.java

@@ -0,0 +1,11 @@
+package com.baeldung.nestedclass;
+
+public class Outer {
+
+    public class Inner {
+
+        public void test() {
+            System.out.println("Calling test...");
+        }
+    }
+}

core-java/src/main/java/com/baeldung/nestedclass/SimpleAbstractClass.java

@@ -0,0 +1,5 @@
+package com.baeldung.nestedclass;
+
+abstract class SimpleAbstractClass {
+    abstract void run();
+}

core-java/src/main/java/com/baeldung/util/StreamUtils.java

@@ -0,0 +1,16 @@
+package com.baeldung.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.StringWriter;
+
+import org.apache.commons.io.IOUtils;
+
+public class StreamUtils {
+
+    public static String getStringFromInputStream(InputStream input) throws IOException {
+        StringWriter writer = new StringWriter();
+        IOUtils.copy(input, writer, "UTF-8");
+        return writer.toString();
+    }
+}

core-java/src/main/resources/countries.properties

@@ -0,0 +1,3 @@
+UK
+US
+Germany

core-java/src/test/java/com/baeldung/file/FileOutputStreamTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.file;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import org.junit.After;
+import org.junit.Test;
+
+import com.baeldung.util.StreamUtils;
+
+public class FileOutputStreamTest {
+
+    public static final String fileName = "src/main/resources/countries.properties";
+
+    @Test
+    public void whenAppendToFileUsingFileOutputStream_thenCorrect() throws Exception {
+        FileOutputStream fos = new FileOutputStream(fileName, true);
+        fos.write("Spain\r\n".getBytes());
+        fos.close();
+
+        assertThat(StreamUtils.getStringFromInputStream(
+          new FileInputStream(fileName)))
+          .isEqualTo("UK\r\n" + "US\r\n" + "Germany\r\n" + "Spain\r\n");
+    }
+
+    @After
+    public void revertFile() throws IOException {
+        PrintWriter writer = new PrintWriter(fileName);
+        writer.print("UK\r\n" + "US\r\n" + "Germany\r\n");
+        writer.close();
+    }
+}

core-java/src/test/java/com/baeldung/file/FileUtilsTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.file;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.After;
+import org.junit.Test;
+
+import com.baeldung.util.StreamUtils;
+
+public class FileUtilsTest {
+
+    public static final String fileName = "src/main/resources/countries.properties";
+
+    @Test
+    public void whenAppendToFileUsingFiles_thenCorrect() throws IOException {
+        File file = new File(fileName);
+        FileUtils.writeStringToFile(file, "Spain\r\n", StandardCharsets.UTF_8, true);
+        
+        assertThat(StreamUtils.getStringFromInputStream(
+          new FileInputStream(fileName)))
+          .isEqualTo("UK\r\n" + "US\r\n" + "Germany\r\n" + "Spain\r\n");
+    }
+    
+    @After
+    public void revertFile() throws IOException {
+        PrintWriter writer = new PrintWriter(fileName);
+        writer.print("UK\r\n" + "US\r\n" + "Germany\r\n");
+        writer.close();
+    }
+}

core-java/src/test/java/com/baeldung/file/FileWriterTest.java

@@ -0,0 +1,40 @@
+package com.baeldung.file;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.BufferedWriter;
+import java.io.FileInputStream;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import org.junit.After;
+import org.junit.Test;
+
+import com.baeldung.util.StreamUtils;
+
+public class FileWriterTest {
+    
+    public static final String fileName = "src/main/resources/countries.properties";
+
+    @Test
+    public void whenAppendToFileUsingFileWriter_thenCorrect() throws IOException {
+        FileWriter fw = new FileWriter(fileName, true);
+        BufferedWriter bw = new BufferedWriter(fw);
+        bw.write("Spain");
+        bw.newLine();
+        bw.close();
+
+        assertThat(
+          StreamUtils.getStringFromInputStream(
+          new FileInputStream(fileName)))
+          .isEqualTo("UK\r\n" + "US\r\n" + "Germany\r\n" + "Spain\n");
+    }
+
+    @After
+    public void revertFile() throws IOException {
+        PrintWriter writer = new PrintWriter(fileName);
+        writer.print("UK\r\n" + "US\r\n" + "Germany\r\n");
+        writer.close();
+    }
+}

core-java/src/test/java/com/baeldung/file/FilesTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.file;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+
+import org.junit.After;
+import org.junit.Test;
+
+import com.baeldung.util.StreamUtils;
+
+public class FilesTest {
+
+    public static final String fileName = "src/main/resources/countries.properties";
+
+    @Test
+    public void whenAppendToFileUsingFiles_thenCorrect() throws IOException {
+        Files.write(Paths.get(fileName), "Spain\r\n".getBytes(), StandardOpenOption.APPEND);
+
+        assertThat(StreamUtils.getStringFromInputStream(
+          new FileInputStream(fileName)))
+          .isEqualTo("UK\r\n" + "US\r\n" + "Germany\r\n" + "Spain\r\n");
+    }
+
+    @After
+    public void revertFile() throws IOException {
+        PrintWriter writer = new PrintWriter(fileName);
+        writer.print("UK\r\n" + "US\r\n" + "Germany\r\n");
+        writer.close();
+    }
+}

core-java/src/test/java/com/baeldung/file/GuavaTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.file;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.baeldung.util.StreamUtils;
+import com.google.common.base.Charsets;
+import com.google.common.io.CharSink;
+import com.google.common.io.FileWriteMode;
+import com.google.common.io.Files;
+
+public class GuavaTest {
+
+    public static final String fileName = "src/main/resources/countries.properties";
+    
+    @Before
+    public void setup() throws Exception {
+        PrintWriter writer = new PrintWriter(fileName);
+        writer.print("UK\r\n" + "US\r\n" + "Germany\r\n");
+        writer.close();
+    }
+
+    @Test
+    public void whenAppendToFileUsingGuava_thenCorrect() throws IOException {
+        File file = new File(fileName);
+        CharSink chs = Files.asCharSink(file, Charsets.UTF_8, FileWriteMode.APPEND);
+        chs.write("Spain\r\n");
+        
+        assertThat(StreamUtils.getStringFromInputStream(
+          new FileInputStream(fileName)))
+          .isEqualTo("UK\r\n" + "US\r\n" + "Germany\r\n" + "Spain\r\n");
+    }
+    
+    @After
+    public void revertFile() throws IOException {
+        PrintWriter writer = new PrintWriter(fileName);
+        writer.print("UK\r\n" + "US\r\n" + "Germany\r\n");
+        writer.close();
+    }
+}

core-java/src/test/java/com/baeldung/nestedclass/AnonymousInnerTest.java

@@ -0,0 +1,16 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class AnonymousInnerTest {
+
+    @Test
+    public void whenRunAnonymousClass_thenCorrect() {
+        SimpleAbstractClass simpleAbstractClass = new SimpleAbstractClass() {
+            void run() {
+                System.out.println("Running Anonymous Class...");
+            }
+        };
+        simpleAbstractClass.run();
+    }
+}

core-java/src/test/java/com/baeldung/nestedclass/InnerClassTest.java

@@ -0,0 +1,13 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class InnerClassTest {
+
+    @Test
+    public void givenInnerClassWhenInstantiating_thenCorrect() {
+        Outer outer = new Outer();
+        Outer.Inner inner = outer.new Inner();
+        inner.test();
+    }
+}

core-java/src/test/java/com/baeldung/nestedclass/LocalClassTest.java

@@ -0,0 +1,12 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class LocalClassTest {
+
+    @Test
+    public void whenTestingLocalClass_thenCorrect() {
+        NewEnclosing newEnclosing = new NewEnclosing();
+        newEnclosing.run();
+    }
+}

core-java/src/test/java/com/baeldung/nestedclass/NestedClassTest.java

@@ -0,0 +1,12 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class NestedClassTest {
+
+    @Test
+    public void whenInstantiatingStaticNestedClass_thenCorrect() {
+        Enclosing.Nested nested = new Enclosing.Nested();
+        nested.test();
+    }
+}

core-java/src/test/java/com/baeldung/nestedclass/NewOuterTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.nestedclass;
+
+import static org.junit.Assert.assertEquals;
+import org.junit.Test;
+
+public class NewOuterTest {
+
+    int a = 1;
+    static int b = 2;
+
+    public class InnerClass {
+        int a = 3;
+        static final int b = 4;
+
+        @Test
+        public void whenShadowing_thenCorrect() {
+            assertEquals(3, a);
+            assertEquals(4, b);
+            assertEquals(1, NewOuterTest.this.a);
+            assertEquals(2, NewOuterTest.b);
+            assertEquals(2, NewOuterTest.this.b);
+        }
+    }
+
+    @Test
+    public void shadowingTest() {
+        NewOuterTest outer = new NewOuterTest();
+        NewOuterTest.InnerClass inner = outer.new InnerClass();
+        inner.whenShadowing_thenCorrect();
+
+    }
+}