example code for BAEL-966 (#2152)

* added updated example codes

* updated example code StringToCharStream

* deleted StringToCharStream.java locally

* removed redundant file

* added code for apache commons collection SetUtils

* refactored example code

core-java/src/test/java/com/baeldung/string/StringToCharStreamUnitTest.java

@@ -12,7 +12,6 @@ import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
-import static org.junit.Assert.assertTrue;
 
 public class StringToCharStreamUnitTest {
 
@@ -44,7 +43,6 @@ public class StringToCharStreamUnitTest {
           .mapToObj(c -> (char) c);
         Stream<Character> characterStream1 = testString.codePoints()
           .mapToObj(c -> (char) c);
-
         assertNotNull("IntStream returned by chars() did not map to Stream<Character>", characterStream);
         assertNotNull("IntStream returned by codePoints() did not map to Stream<Character>", characterStream1);
     }

libraries/pom.xml

@@ -90,6 +90,11 @@
             <artifactId>commons-lang3</artifactId>
             <version>${commons-lang.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons.collections.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.jasypt</groupId>
             <artifactId>jasypt</artifactId>
@@ -340,13 +345,17 @@
             <artifactId>opennlp-tools</artifactId>
             <version>1.8.0</version>
         </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>info.debatty</groupId>
             <artifactId>java-lsh</artifactId>
             <version>${java-lsh.version}</version>
         </dependency>
-
-
     </dependencies>
     <properties>
         <multiverse.version>0.7.0</multiverse.version>
@@ -373,6 +382,8 @@
         <serenity.plugin.version>1.4.0</serenity.plugin.version>
         <jUnitParams.version>1.1.0</jUnitParams.version>
         <netty.version>4.1.10.Final</netty.version>
+        <commons.collections.version>4.1</commons.collections.version>
+        <junit.version>4.12</junit.version>
         <java-lsh.version>0.10</java-lsh.version>
     </properties>
 

libraries/src/test/java/com/baeldung/commons/collections/SetUtilsUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.commons.collections;
+
+import org.apache.commons.collections4.SetUtils;
+import org.apache.commons.collections4.set.TransformedSet;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Created by smatt on 21/06/2017.
+ */
+public class SetUtilsUnitTest {
+
+    @Test(expected = IllegalArgumentException.class)
+    public void givenSetAndPredicate_whenPredicatedSet_thenValidateSet_and_throw_IllegalArgumentException() {
+        Set<String> sourceSet = new HashSet<>();
+        sourceSet.addAll(Arrays.asList("London", "Lagos", "Err Source1"));
+        Set<String> validatingSet
+          = SetUtils.predicatedSet(sourceSet, (s) -> s.startsWith("L"));
+        validatingSet.add("Err Source2");
+    }
+
+    @Test
+    public void givenTwoSets_whenDifference_thenSetView() {
+        Set<Integer> a = new HashSet<>(Arrays.asList(1,2,5));
+        Set<Integer> b = new HashSet<>(Arrays.asList(1,2));
+        SetUtils.SetView<Integer> result = SetUtils.difference(a, b);
+        assertTrue(result.size() == 1 && result.contains(5));
+    }
+
+    @Test
+    public void givenTwoSets_whenUnion_thenUnionResult() {
+        Set<Integer> a = new HashSet<>(Arrays.asList(1,2,5));
+        Set<Integer> b = new HashSet<>(Arrays.asList(1,2));
+        Set<Integer> expected = new HashSet<>(Arrays.asList(1,2,5));
+        SetUtils.SetView<Integer> union = SetUtils.union(a, b);
+        assertTrue(SetUtils.isEqualSet(expected, union));
+    }
+
+    @Test
+    public void givenTwoSets_whenIntersection_thenIntersectionResult() {
+        Set<Integer> a = new HashSet<>(Arrays.asList(1,2,5));
+        Set<Integer> b = new HashSet<>(Arrays.asList(1,2));
+        Set<Integer> expected = new HashSet<>(Arrays.asList(1,2));
+        SetUtils.SetView<Integer> intersect = SetUtils.intersection(a, b);
+        assertTrue(SetUtils.isEqualSet(expected, intersect));
+    }
+
+    @Test
+    public void givenSet_whenTransformedSet_thenTransformedResult() {
+        Set<Integer> a = SetUtils.transformedSet(new HashSet<>(), (e) -> e * 2  );
+        a.add(2);
+        assertEquals(a.toArray()[0], 4);
+
+        Set<Integer> source = new HashSet<>(Arrays.asList(1));
+        Set<Integer> newSet = TransformedSet.transformedSet(source, (e) -> e * 2);
+        assertEquals(newSet.toArray()[0], 2);
+        assertEquals(source.toArray()[0], 2);
+    }
+
+    @Test
+    public void givenTwoSet_whenDisjunction_thenDisjunctionSet() {
+        Set<Integer> a = new HashSet<>(Arrays.asList(1,2,5));
+        Set<Integer> b = new HashSet<>(Arrays.asList(1,2,3));
+        SetUtils.SetView<Integer> result = SetUtils.disjunction(a, b);
+        assertTrue(result.toSet().contains(5) && result.toSet().contains(3));
+    }
+
+    @Test
+    public void givenSet_when_OrderedSet_thenMaintainElementOrder() {
+        Set<Integer> set = new HashSet<>(Arrays.asList(10,1,5));
+        System.out.println("unordered set: " + set);
+
+        Set<Integer> orderedSet = SetUtils.orderedSet(new HashSet<>());
+        orderedSet.addAll(Arrays.asList(10,1,5));
+        System.out.println("ordered set = " + orderedSet);
+    }
+}