Request for BAEL-1584

core-java-8/src/main/java/com/baeldung/findanelement/FindElementInAList.java

@@ -0,0 +1,71 @@
+package com.baeldung.findanelement;
+
+import java.util.List;
+import java.util.ListIterator;
+import org.apache.commons.collections4.IterableUtils;
+import com.google.common.base.Predicate;
+import com.google.common.collect.Iterables;
+
+public class FindElementInAList<T> {
+
+    public T findUsingIndexOf(T element, List<T> list) {
+        int index = list.indexOf(element);
+        if (index >= 0) {
+            return element;
+        }
+        return null;
+    }
+
+    public boolean findUsingListIterator(T element, List<T> list) {
+        ListIterator<T> listIterator = list.listIterator();
+        while (listIterator.hasNext()) {
+            T elementFromList = listIterator.next();
+            if (elementFromList.equals(element)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public boolean findUsingEnhancedForLoop(T element, List<T> list) {
+        for (T elementFromList : list) {
+            if (element.equals(elementFromList)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public T findUsingStream(T element, List<T> list) {
+        return list.stream()
+            .filter(integer -> integer.equals(element))
+            .findFirst()
+            .orElse(null);
+    }
+
+    public T findUsingParallelStream(T element, List<T> list) {
+        return list.parallelStream()
+            .filter(integer -> integer.equals(element))
+            .findAny()
+            .orElse(null);
+    }
+
+    public T findUsingGuava(T element, List<T> list) {
+        T foundElement = Iterables.tryFind(list, new Predicate<T>() {
+            public boolean apply(T input) {
+                return element.equals(input);
+            }
+        }).orNull();
+        return foundElement;
+    }
+
+    public T findUsingApacheCommon(T element, List<T> list) {
+        T foundElement = IterableUtils.find(list, new org.apache.commons.collections4.Predicate<T>() {
+            public boolean evaluate(T input) {
+                return element.equals(input);
+            }
+        });
+        return foundElement;
+    }
+
+}

core-java-8/src/test/java/com/baeldung/findanelement/FindAnElementTest.java

@@ -0,0 +1,116 @@
+package com.baeldung.findanelement;
+
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.Test;
+
+public class FindAnElementTest {
+
+    private static List<Integer> scores = new ArrayList<>();
+    static {
+        scores.add(0);
+        scores.add(1);
+        scores.add(2);
+    }
+
+    private static FindElementInAList<Integer> findElementInAList = new FindElementInAList<>();
+
+    @Test
+    public void givenElement_whenFoundUsingIndexOf_thenReturnElement() {
+        Integer scoreToFind = 1;
+        Integer score = findElementInAList.findUsingIndexOf(scoreToFind, scores);
+        assertTrue(score.equals(scoreToFind));
+    }
+
+    @Test
+    public void givenElement_whenNotFoundUsingListIterator_thenReturnNull() {
+        boolean found = findElementInAList.findUsingListIterator(5, scores);
+        assertTrue(!found);
+    }
+
+    @Test
+    public void givenElement_whenFoundListIterator_thenReturnElement() {
+        Integer scoreToFind = 1;
+        boolean found = findElementInAList.findUsingListIterator(scoreToFind, scores);
+        assertTrue(found);
+    }
+
+    @Test
+    public void givenElement_whenNotFoundUsingIndexOf_thenReturnNull() {
+        Integer score = findElementInAList.findUsingIndexOf(5, scores);
+        assertNull(score);
+    }
+
+    @Test
+    public void givenElement_whenFoundUsingEnhancedForLoop_thenReturnElement() {
+        Integer scoreToFind = 1;
+        boolean found = findElementInAList.findUsingEnhancedForLoop(scoreToFind, scores);
+        assertTrue(found);
+    }
+
+    @Test
+    public void givenElement_whenNotFoundUsingEnhancedForLoop_thenReturnNull() {
+        Integer scoreToFind = 5;
+        boolean found = findElementInAList.findUsingEnhancedForLoop(scoreToFind, scores);
+        assertTrue(!found);
+    }
+
+    @Test
+    public void givenElement_whenFoundUsingStream_thenReturnElement() {
+        Integer scoreToFind = 1;
+        Integer score = findElementInAList.findUsingStream(scoreToFind, scores);
+        assertTrue(score.equals(scoreToFind));
+    }
+
+    @Test
+    public void givenElement_whenNotFoundUsingStream_thenReturnNull() {
+        Integer scoreToFind = 5;
+        Integer score = findElementInAList.findUsingStream(scoreToFind, scores);
+        assertNull(score);
+    }
+
+    @Test
+    public void givenElement_whenFoundUsingParallelStream_thenReturnElement() {
+        Integer scoreToFind = 1;
+        Integer score = findElementInAList.findUsingParallelStream(scoreToFind, scores);
+        assertTrue(score.equals(scoreToFind));
+    }
+
+    @Test
+    public void givenElement_whenNotFoundUsingParallelStream_thenReturnNull() {
+        Integer scoreToFind = 5;
+        Integer score = findElementInAList.findUsingParallelStream(scoreToFind, scores);
+        assertNull(score);
+    }
+
+    @Test
+    public void givenElement_whenFoundUsingGuava_thenReturnElement() {
+        Integer scoreToFind = 1;
+        Integer score = findElementInAList.findUsingGuava(scoreToFind, scores);
+        assertTrue(score.equals(scoreToFind));
+    }
+
+    @Test
+    public void givenElement_whenNotFoundUsingGuava_thenReturnNull() {
+        Integer scoreToFind = 5;
+        Integer score = findElementInAList.findUsingGuava(scoreToFind, scores);
+        assertNull(score);
+    }
+
+    @Test
+    public void givenElement_whenFoundUsingApacheCommons_thenReturnElement() {
+        Integer scoreToFind = 1;
+        Integer score = findElementInAList.findUsingApacheCommon(scoreToFind, scores);
+        assertTrue(score.equals(scoreToFind));
+    }
+
+    @Test
+    public void givenElement_whenNotFoundUsingApacheCommons_thenReturnNull() {
+        Integer scoreToFind = 5;
+        Integer score = findElementInAList.findUsingApacheCommon(scoreToFind, scores);
+        assertNull(score);
+    }
+
+}