[BAEL-10836] - Moved Java8CollectionCleanupUnitTest, AddElementsUnitTest and articles

core-java-collections-list/src/main/java/com/baeldung/list/Flower.java

@@ -0,0 +1,28 @@
+package com.baeldung.list;
+
+public class Flower {
+
+    private String name;
+    private int petals;
+
+    public Flower(String name, int petals) {
+        this.name = name;
+        this.petals = petals;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getPetals() {
+        return petals;
+    }
+
+    public void setPetals(int petals) {
+        this.petals = petals;
+    }
+}

core-java-collections-list/src/test/java/com/baeldung/java8/Java8CollectionCleanupUnitTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.java8;
+
+import com.google.common.collect.Lists;
+import org.junit.Test;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+import static org.hamcrest.Matchers.hasSize;
+import static org.junit.Assert.assertThat;
+
+public class Java8CollectionCleanupUnitTest {
+
+    // tests -
+
+    @Test
+    public void givenListContainsNulls_whenFilteringParallel_thenCorrect() {
+        final List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
+        final List<Integer> listWithoutNulls = list.parallelStream().filter(Objects::nonNull).collect(Collectors.toList());
+
+        assertThat(listWithoutNulls, hasSize(3));
+    }
+
+    @Test
+    public void givenListContainsNulls_whenFilteringSerial_thenCorrect() {
+        final List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
+        final List<Integer> listWithoutNulls = list.stream().filter(Objects::nonNull).collect(Collectors.toList());
+
+        assertThat(listWithoutNulls, hasSize(3));
+    }
+
+    @Test
+    public void givenListContainsNulls_whenRemovingNullsWithRemoveIf_thenCorrect() {
+        final List<Integer> listWithoutNulls = Lists.newArrayList(null, 1, 2, null, 3, null);
+        listWithoutNulls.removeIf(Objects::isNull);
+
+        assertThat(listWithoutNulls, hasSize(3));
+    }
+
+    @Test
+    public void givenListContainsDuplicates_whenRemovingDuplicatesWithJava8_thenCorrect() {
+        final List<Integer> listWithDuplicates = Lists.newArrayList(1, 1, 2, 2, 3, 3);
+        final List<Integer> listWithoutDuplicates = listWithDuplicates.parallelStream().distinct().collect(Collectors.toList());
+
+        assertThat(listWithoutDuplicates, hasSize(3));
+    }
+
+}

core-java-collections-list/src/test/java/com/baeldung/list/AddElementsUnitTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.list;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.*;
+
+import static org.junit.Assert.*;
+
+public class AddElementsUnitTest {
+
+    List<Flower> flowers;
+
+    @Before
+    public void init() {
+        this.flowers = new ArrayList<>(Arrays.asList(
+                new Flower("Poppy", 12),
+                new Flower("Anemone", 8),
+                new Flower("Catmint", 12)));
+    }
+
+    @Test
+    public void givenAList_whenTargetListIsEmpty_thenReturnTargetListWithNewItems() {
+        List<Flower> anotherList = new ArrayList<>();
+        anotherList.addAll(flowers);
+
+        assertEquals(anotherList.size(), flowers.size());
+        Assert.assertTrue(anotherList.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenTargetListIsEmpty_thenReturnTargetListWithOneModifiedElementByConstructor() {
+        List<Flower> anotherList = new ArrayList<>();
+        anotherList.addAll(flowers);
+
+        Flower flower = anotherList.get(0);
+        flower.setPetals(flowers.get(0).getPetals() * 3);
+
+        assertEquals(anotherList.size(), flowers.size());
+        Assert.assertTrue(anotherList.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAListAndElements_whenUseCollectionsAddAll_thenAddElementsToTargetList() {
+        List<Flower> target = new ArrayList<>();
+
+        Collections.addAll(target, flowers.get(0), flowers.get(1), flowers.get(2), flowers.get(0));
+
+        assertEquals(target.size(), 4);
+    }
+
+    @Test
+    public void givenTwoList_whenSourceListDoesNotHaveNullElements_thenAddElementsToTargetListSkipFirstElementByStreamProcess() {
+        List<Flower> flowerVase = new ArrayList<>();
+
+        flowers.stream()
+                .skip(1)
+                .forEachOrdered(flowerVase::add);
+
+        assertEquals(flowerVase.size() + 1, flowers.size());
+        assertFalse(flowerVase.containsAll(flowers));
+    }
+
+    @Test
+    public void givenTwoList_whenSourceListDoesNotHaveNullElements_thenAddElementsToTargetListFilteringElementsByStreamProcess() {
+        List<Flower> flowerVase = new ArrayList<>();
+
+        flowers.stream()
+                .filter(f -> f.getPetals() > 10)
+                .forEachOrdered(flowerVase::add);
+
+        assertEquals(flowerVase.size() + 1, flowers.size());
+        assertFalse(flowerVase.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListIsNotNull_thenAddElementsToListByStreamProcessWihtOptional() {
+        List<Flower> target = new ArrayList<>();
+
+        Optional.ofNullable(flowers)
+                .ifPresent(target::addAll);
+
+        assertNotNull(target);
+        assertEquals(target.size(), 3);
+    }
+}