BAEL-2837 Add sample Set operations in Java (#6697)

* BAEL-2837: Add sample set operations in Java * BAEL-2837 add new module core-java-collections-set * BAEL-2837 Updated readme.md file * BAEL-2837 Tidy dependencies in pom.xml * BAEL-2837 tidy white space in pom.xml * BAEL-2837 Rename unit test class * BAEL-2837 Removed unused logback-xml
2019-04-22 18:12:56 +01:00
parent 49a806e787
commit b63f8882ea
4 changed files with 134 additions and 0 deletions
@@ -0,0 +1,93 @@
+package com.baeldung.set;
+
+import static org.junit.Assert.*;
+
+import org.apache.commons.collections4.SetUtils;
+import org.junit.Test;
+
+import com.google.common.collect.Sets;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class SetOperationsUnitTest {
+
+    private Set<Integer> setA = setOf(1,2,3,4);
+    private Set<Integer> setB = setOf(2,4,6,8);
+    
+    private static Set<Integer> setOf(Integer... values) {
+        return new HashSet<Integer>(Arrays.asList(values));
+    }
+    
+    @Test
+    public void givenTwoSets_WhenWeRetainAll_ThenWeIntersectThem() {
+        Set<Integer> intersectSet = new HashSet<>(setA);
+        intersectSet.retainAll(setB);
+        assertEquals(setOf(2,4), intersectSet);
+    }
+    
+    @Test
+    public void givenTwoSets_WhenWeAddAll_ThenWeUnionThem() {
+        Set<Integer> unionSet = new HashSet<>(setA);
+        unionSet.addAll(setB);
+        assertEquals(setOf(1,2,3,4,6,8), unionSet);
+    }
+    
+    @Test
+    public void givenTwoSets_WhenRemoveAll_ThenWeGetTheDifference() {
+        Set<Integer> differenceSet = new HashSet<>(setA);
+        differenceSet.removeAll(setB);
+        assertEquals(setOf(1,3), differenceSet);
+    }
+    
+    @Test
+    public void givenTwoStreams_WhenWeFilterThem_ThenWeCanGetTheIntersect() {
+        Set<Integer> intersectSet = setA.stream()
+            .filter(setB::contains)
+            .collect(Collectors.toSet());
+        assertEquals(setOf(2,4), intersectSet);
+    }
+    
+    @Test
+    public void givenTwoStreams_WhenWeConcatThem_ThenWeGetTheUnion() {
+        Set<Integer> unionSet = Stream.concat(setA.stream(), setB.stream())
+            .collect(Collectors.toSet());
+        assertEquals(setOf(1,2,3,4,6,8), unionSet);
+    }
+    
+    @Test
+    public void givenTwoStreams_WhenWeFilterThem_ThenWeCanGetTheDifference() {
+        Set<Integer> differenceSet = setA.stream()
+            .filter(val -> !setB.contains(val))
+            .collect(Collectors.toSet());
+        assertEquals(setOf(1,3), differenceSet);
+    }
+    
+    @Test
+    public void givenTwoSets_WhenWeUseApacheCommonsIntersect_ThenWeGetTheIntersect() {
+        Set<Integer> intersectSet = SetUtils.intersection(setA, setB);
+        assertEquals(setOf(2,4), intersectSet);
+    }
+    
+    @Test
+    public void givenTwoSets_WhenWeUseApacheCommonsUnion_ThenWeGetTheUnion() {
+        Set<Integer> unionSet = SetUtils.union(setA, setB);
+        assertEquals(setOf(1,2,3,4,6,8), unionSet);
+    }
+    
+    
+    @Test
+    public void givenTwoSets_WhenWeUseGuavaIntersect_ThenWeGetTheIntersect() {
+        Set<Integer> intersectSet = Sets.intersection(setA, setB);
+        assertEquals(setOf(2,4), intersectSet);
+    }
+    
+    @Test
+    public void givenTwoSets_WhenWeUseGuavaUnion_ThenWeGetTheUnion() {
+        Set<Integer> unionSet = Sets.union(setA, setB);
+        assertEquals(setOf(1,2,3,4,6,8), unionSet);
+    }
+}