BAEL-2181 complete commit (eugenp#5294)

Author: ramansahasi

core-java-collections/pom.xml

@@ -63,6 +63,12 @@
             <artifactId>jmh-generator-annprocess</artifactId>
             <version>${openjdk.jmh.version}</version>
         </dependency>
+		<dependency>
+		    <groupId>org.apache.commons</groupId>
+		    <artifactId>commons-exec</artifactId>
+		    <version>1.3</version>
+		</dependency>
+		        
     </dependencies>
 
 

core-java-collections/src/main/java/com/baeldung/combiningcollections/CombiningArrays.java

@@ -0,0 +1,39 @@
+package com.baeldung.combiningcollections;
+
+import java.util.Arrays;
+import java.util.stream.Stream;
+
+import org.apache.commons.lang3.ArrayUtils;
+
+import com.google.common.collect.ObjectArrays;
+
+public class CombiningArrays {
+    
+    public static Object[] usingNativeJava(Object[] first, Object[] second) {
+        Object[] combined = new Object[first.length + second.length];
+        System.arraycopy(first, 0, combined, 0, first.length);
+        System.arraycopy(second, 0, combined, first.length, second.length);
+        return combined;
+    }
+    
+    public static Object[] usingJava8ObjectStream(Object[] first, Object[] second) {
+        Object[] combined = Stream.concat(Arrays.stream(first), Arrays.stream(second)).toArray();
+        return combined;
+    }
+
+    public static Object[] usingJava8FlatMaps(Object[] first, Object[] second) {
+        Object[] combined = Stream.of(first, second).flatMap(Stream::of).toArray(String[]::new);
+        return combined;
+    }
+    
+    public static Object[] usingApacheCommons(Object[] first, Object[] second) {
+        Object[] combined = ArrayUtils.addAll(first, second);
+        return combined;
+    }
+
+    public static Object[] usingGuava(Object[] first, Object[] second) {
+        Object [] combined = ObjectArrays.concat(first, second, Object.class);
+        return combined;
+    }
+    
+}

core-java-collections/src/main/java/com/baeldung/combiningcollections/CombiningLists.java

@@ -0,0 +1,46 @@
+package com.baeldung.combiningcollections;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.apache.commons.collections4.ListUtils;
+
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Lists;
+
+public class CombiningLists {
+    
+    public static List<Object> usingNativeJava(List<Object> first, List<Object> second) {
+        List<Object> combined = new ArrayList<>();
+        combined.addAll(first);
+        combined.addAll(second);
+        return combined;
+    }
+    
+    public static List<Object> usingJava8ObjectStream(List<Object> first, List<Object> second) {
+        List<Object> combined = Stream.concat(first.stream(), second.stream()).collect(Collectors.toList());
+        return combined;
+    }
+
+    public static List<Object> usingJava8FlatMaps(List<Object> first, List<Object> second) {
+        List<Object> combined = Stream.of(first, second).flatMap(Collection::stream).collect(Collectors.toList());
+        return combined;
+    }
+    
+    public static List<Object> usingApacheCommons(List<Object> first, List<Object> second) {
+        List<Object> combined = ListUtils.union(first, second);
+        return combined;
+    }
+
+    public static List<Object> usingGuava(List<Object> first, List<Object> second) {
+        Iterable<Object> combinedIterables = Iterables.unmodifiableIterable(
+        Iterables.concat(first, second));
+        
+        List<Object> combined = Lists.newArrayList(combinedIterables);
+        return combined;
+    }
+    
+}

core-java-collections/src/main/java/com/baeldung/combiningcollections/CombiningMaps.java

@@ -0,0 +1,47 @@
+package com.baeldung.combiningcollections;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.apache.commons.exec.util.MapUtils;
+
+import com.google.common.collect.ImmutableMap;
+
+public class CombiningMaps {
+    
+    public static Map<String, String> usingPlainJava(Map<String, String> first, Map<String, String> second) {
+    	Map<String, String> combined = new HashMap<>();
+    	combined.putAll(first);
+    	combined.putAll(second);
+        return combined;
+    }
+    
+    public static Map<String, String> usingJava8ForEach(Map<String, String> first, Map<String, String> second) {
+    	second.forEach((key, value) -> first.merge(key, value, String::concat));
+        return first;
+    }
+
+    public static Map<String, String> usingJava8FlatMaps(Map<String, String> first, Map<String, String> second) {
+		Map<String, String> combined = Stream.of(first, second).map(Map::entrySet).flatMap(Collection::stream)
+				.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, String::concat));
+		return combined;
+
+    }
+    
+    public static Map<String, String> usingApacheCommons(Map<String, String> first, Map<String, String> second) {
+        Map<String, String> combined = MapUtils.merge(first, second);
+        return combined;
+    }
+
+    public static Map<String, String> usingGuava(Map<String, String> first, Map<String, String> second) {
+        Map<String, String> combined = ImmutableMap.<String, String>builder()
+          .putAll(first)
+          .putAll(second)
+          .build();
+        return combined;
+    }
+    
+}

core-java-collections/src/main/java/com/baeldung/combiningcollections/CombiningSets.java

@@ -0,0 +1,42 @@
+package com.baeldung.combiningcollections;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.apache.commons.collections4.SetUtils;
+
+import com.google.common.collect.Sets;
+
+public class CombiningSets {
+    
+    public static Set<Object> usingNativeJava(Set<Object> first, Set<Object> second) {
+        Set<Object> combined = new HashSet<>();
+        combined.addAll(first);
+        combined.addAll(second);
+        return combined;
+    }
+    
+    public static Set<Object> usingJava8ObjectStream(Set<Object> first, Set<Object> second) {
+        Set<Object> combined = Stream.concat(first.stream(), second.stream()).collect(Collectors.toSet());
+        return combined;
+    }
+
+    public static Set<Object> usingJava8FlatMaps(Set<Object> first, Set<Object> second) {
+        Set<Object> combined = Stream.of(first, second).flatMap(Collection::stream).collect(Collectors.toSet());
+        return combined;
+    }
+    
+    public static Set<Object> usingApacheCommons(Set<Object> first, Set<Object> second) {
+        Set<Object> combined = SetUtils.union(first, second);
+        return combined;
+    }
+
+    public static Set<Object> usingGuava(Set<Object> first, Set<Object> second) {
+        Set<Object> combined = Sets.union(first, second);
+        return combined;
+    }
+    
+}

core-java-collections/src/test/java/com/baeldung/combiningcollections/CombiningArraysUnitTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.combiningcollections;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+
+public class CombiningArraysUnitTest {
+    private static final String first[] = {
+            "One", 
+            "Two", 
+            "Three"
+    };
+    
+    private static final String second[] = {
+            "Four", 
+            "Five", 
+            "Six"
+    };
+
+    private static final String expected[] = {
+            "One", 
+            "Two", 
+            "Three",
+            "Four", 
+            "Five", 
+            "Six"
+    };
+    
+    @Test
+    public void givenTwoArrays_whenUsingNativeJava_thenArraysCombined() {
+        assertArrayEquals(expected, CombiningArrays.usingNativeJava(first, second));
+    }
+
+    @Test
+    public void givenTwoArrays_whenUsingObjectStreams_thenArraysCombined() {
+        assertArrayEquals(expected, CombiningArrays.usingJava8ObjectStream(first, second));
+    }
+
+    @Test
+    public void givenTwoArrays_whenUsingFlatMaps_thenArraysCombined() {
+        assertArrayEquals(expected, CombiningArrays.usingJava8FlatMaps(first, second));
+    }
+
+    @Test
+    public void givenTwoArrays_whenUsingApacheCommons_thenArraysCombined() {
+        assertArrayEquals(expected, CombiningArrays.usingApacheCommons(first, second));
+    }
+
+    @Test
+    public void givenTwoArrays_whenUsingGuava_thenArraysCombined() {
+        assertArrayEquals(expected, CombiningArrays.usingGuava(first, second));
+    }
+}

core-java-collections/src/test/java/com/baeldung/combiningcollections/CombiningListsUnitTest.java

@@ -0,0 +1,57 @@
+package com.baeldung.combiningcollections;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+
+public class CombiningListsUnitTest {
+    private static final List<Object> first = Arrays.asList(new Object[]{
+            "One", 
+            "Two", 
+            "Three"
+    });
+    
+    private static final List<Object> second = Arrays.asList(new Object[]{
+            "Four", 
+            "Five", 
+            "Six"
+    });
+
+    private static final List<Object> expected = Arrays.asList(new Object[]{
+            "One", 
+            "Two", 
+            "Three",
+            "Four", 
+            "Five", 
+            "Six"
+    });
+    
+    @Test
+    public void givenTwoLists_whenUsingNativeJava_thenArraysCombined() {
+    	assertThat(CombiningLists.usingNativeJava(first, second), is(expected));
+    }
+
+    @Test
+    public void givenTwoLists_whenUsingObjectStreams_thenArraysCombined() {
+        assertThat(CombiningLists.usingJava8ObjectStream(first, second), is(expected));
+    }
+
+    @Test
+    public void givenTwoLists_whenUsingFlatMaps_thenArraysCombined() {
+        assertThat(CombiningLists.usingJava8FlatMaps(first, second), is(expected));
+    }
+
+    @Test
+    public void givenTwoLists_whenUsingApacheCommons_thenArraysCombined() {
+        assertThat(CombiningLists.usingApacheCommons(first, second), is(expected));
+    }
+
+    @Test
+    public void givenTwoLists_whenUsingGuava_thenArraysCombined() {
+        assertThat(CombiningLists.usingGuava(first, second), is(expected));
+    }
+}

core-java-collections/src/test/java/com/baeldung/combiningcollections/CombiningMapsUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.combiningcollections;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Test;
+
+public class CombiningMapsUnitTest {
+    private static final Map<String, String> first = new HashMap<>();
+    private static final Map<String, String> second = new HashMap<>();
+    private static Map<String, String> expected = new HashMap<>();
+    
+    static {
+    	first.put("one", "first String");
+    	first.put("two", "second String");
+    	
+    	second.put("three", "third String");
+    	second.put("four", "fourth String");
+
+    	expected.put("one", "first String");
+    	expected.put("two", "second String");
+    	expected.put("three", "third String");
+    	expected.put("four", "fourth String");
+    }
+    
+    @Test
+    public void givenTwoMaps_whenUsingNativeJava_thenMapsCombined() {
+    	assertThat(CombiningMaps.usingPlainJava(first, second), is(expected));
+    }
+
+    
+    @Test
+    public void givenTwoMaps_whenUsingForEach_thenMapsCombined() {
+    	assertThat(CombiningMaps.usingJava8ForEach(first, second), is(expected));
+    }
+    
+    @Test
+    public void givenTwoMaps_whenUsingFlatMaps_thenMapsCombined() {
+    	assertThat(CombiningMaps.usingJava8FlatMaps(first, second), is(expected));
+    }
+    
+    @Test
+    public void givenTwoMaps_whenUsingApacheCommons_thenMapsCombined() {
+    	assertThat(CombiningMaps.usingApacheCommons(first, second), is(expected));
+    }
+    
+    @Test
+    public void givenTwoMaps_whenUsingGuava_thenMapsCombined() {
+    	assertThat(CombiningMaps.usingGuava(first, second), is(expected));
+    }
+}