diff --git a/core-java-8/src/main/java/com/baeldung/list/RemoveAll.java b/core-java-8/src/main/java/com/baeldung/list/RemoveAll.java new file mode 100644 index 000000000000..0dd97af6e842 --- /dev/null +++ b/core-java-8/src/main/java/com/baeldung/list/RemoveAll.java @@ -0,0 +1,111 @@ +package com.baeldung.list; + +import java.util.ArrayList; +import java.util.Iterator; +import java.util.List; +import java.util.Objects; +import java.util.stream.Collectors; + +public class RemoveAll { + + static void removeWithWhileLoopPrimitiveElement(List list, int element) { + while (list.contains(element)) { + list.remove(element); + } + } + + static void removeWithWhileLoopNonPrimitiveElement(List list, Integer element) { + while (list.contains(element)) { + list.remove(element); + } + } + + static void removeWithWhileLoopStoringFirstOccurrenceIndex(List list, Integer element) { + int index; + while ((index = list.indexOf(element)) >= 0) { + list.remove(index); + } + } + + static void removeWithCallingRemoveUntilModifies(List list, Integer element) { + while (list.remove(element)) + ; + } + + static void removeWithStandardForLoopUsingIndex(List list, int element) { + for (int i = 0; i < list.size(); i++) { + if (Objects.equals(element, list.get(i))) { + list.remove(i); + } + } + } + + static void removeWithForLoopDecrementOnRemove(List list, int element) { + for (int i = 0; i < list.size(); i++) { + if (Objects.equals(element, list.get(i))) { + list.remove(i); + i--; + } + } + } + + static void removeWithForLoopIncrementIfRemains(List list, int element) { + for (int i = 0; i < list.size();) { + if (Objects.equals(element, list.get(i))) { + list.remove(i); + } else { + i++; + } + } + } + + static void removeWithForEachLoop(List list, int element) { + for (Integer number : list) { + if (Objects.equals(number, element)) { + list.remove(number); + } + } + } + + static void removeWithIterator(List list, int element) { + for (Iterator i = list.iterator(); i.hasNext();) { + Integer number = i.next(); + if (Objects.equals(number, element)) { + i.remove(); + } + } + } + + static List removeWithCollectingAndReturningRemainingElements(List list, int element) { + List remainingElements = new ArrayList<>(); + for (Integer number : list) { + if (!Objects.equals(number, element)) { + remainingElements.add(number); + } + } + return remainingElements; + } + + static void removeWithCollectingRemainingElementsAndAddingToOriginalList(List list, int element) { + List remainingElements = new ArrayList<>(); + for (Integer number : list) { + if (!Objects.equals(number, element)) { + remainingElements.add(number); + } + } + + list.clear(); + list.addAll(remainingElements); + } + + static List removeWithStreamFilter(List list, Integer element) { + return list.stream() + .filter(e -> !Objects.equals(e, element)) + .collect(Collectors.toList()); + } + + static void removeWithRemoveIf(List list, Integer element) { + list.removeIf(n -> Objects.equals(n, element)); + } + +} diff --git a/core-java-8/src/test/java/com/baeldung/list/RemoveAllUnitTest.java b/core-java-8/src/test/java/com/baeldung/list/RemoveAllUnitTest.java new file mode 100644 index 000000000000..7ada66a49ec5 --- /dev/null +++ b/core-java-8/src/test/java/com/baeldung/list/RemoveAllUnitTest.java @@ -0,0 +1,208 @@ +package com.baeldung.list; + +import static com.baeldung.list.RemoveAll.removeWithCallingRemoveUntilModifies; +import static com.baeldung.list.RemoveAll.removeWithCollectingAndReturningRemainingElements; +import static com.baeldung.list.RemoveAll.removeWithCollectingRemainingElementsAndAddingToOriginalList; +import static com.baeldung.list.RemoveAll.removeWithForEachLoop; +import static com.baeldung.list.RemoveAll.removeWithForLoopDecrementOnRemove; +import static com.baeldung.list.RemoveAll.removeWithForLoopIncrementIfRemains; +import static com.baeldung.list.RemoveAll.removeWithIterator; +import static com.baeldung.list.RemoveAll.removeWithRemoveIf; +import static com.baeldung.list.RemoveAll.removeWithStandardForLoopUsingIndex; +import static com.baeldung.list.RemoveAll.removeWithStreamFilter; +import static com.baeldung.list.RemoveAll.*; + +import static org.assertj.core.api.Assertions.*; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.ConcurrentModificationException; +import java.util.List; + +import org.junit.Test; + +public class RemoveAllUnitTest { + + private List list(Integer... elements) { + return new ArrayList<>(Arrays.asList(elements)); + } + + @Test + public void givenAList_whenRemovingElementsWithWhileLoopUsingPrimitiveElement_thenTheResultCorrect() { + // given + List list = list(1, 2, 3); + int valueToRemove = 1; + + // when + assertThatThrownBy(() -> removeWithWhileLoopPrimitiveElement(list, valueToRemove)) + .isInstanceOf(IndexOutOfBoundsException.class); + } + + @Test + public void givenAList_whenRemovingElementsWithWhileLoopUsingNonPrimitiveElement_thenTheResultCorrect() { + // given + List list = list(1, 2, 3); + int valueToRemove = 1; + + // when + removeWithWhileLoopNonPrimitiveElement(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAList_whenRemovingElementsWithWhileLoopStoringFirstOccurrenceIndex_thenTheResultCorrect() { + // given + List list = list(1, 2, 3); + int valueToRemove = 1; + + // when + removeWithWhileLoopStoringFirstOccurrenceIndex(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAList_whenRemovingElementsWithCallingRemoveUntilModifies_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + removeWithCallingRemoveUntilModifies(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAListWithoutDuplication_whenRemovingElementsWithStandardForLoopUsingIndex_thenTheResultIsCorrect() { + // given + List list = list(1, 2, 3); + int valueToRemove = 1; + + // when + removeWithStandardForLoopUsingIndex(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAListWithAdjacentElements_whenRemovingElementsWithStandardForLoop_thenTheResultIsInCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + removeWithStandardForLoopUsingIndex(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(1, 2, 3)); + } + + @Test + public void givenAListWithAdjacentElements_whenRemovingElementsWithForLoopAndDecrementOnRemove_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + removeWithForLoopDecrementOnRemove(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAListWithAdjacentElements_whenRemovingElementsWithForLoopAndIncrementIfRemains_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + removeWithForLoopIncrementIfRemains(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAList_whenRemovingElementsWithForEachLoop_thenExceptionIsThrown() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + assertThatThrownBy(() -> removeWithForEachLoop(list, valueToRemove)) + .isInstanceOf(ConcurrentModificationException.class); + } + + @Test + public void givenAList_whenRemovingElementsWithIterator_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + removeWithIterator(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAList_whenRemovingElementsWithCollectingAndReturningRemainingElements_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + List result = removeWithCollectingAndReturningRemainingElements(list, valueToRemove); + + // then + assertThat(result).isEqualTo(list(2, 3)); + } + + @Test + public void givenAList_whenRemovingElementsWithCollectingRemainingAndAddingToOriginalList_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + removeWithCollectingRemainingElementsAndAddingToOriginalList(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + + @Test + public void givenAList_whenRemovingElementsWithStreamFilter_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + List result = removeWithStreamFilter(list, valueToRemove); + + // then + assertThat(result).isEqualTo(list(2, 3)); + } + + @Test + public void givenAList_whenRemovingElementsWithCallingRemoveIf_thenTheResultIsCorrect() { + // given + List list = list(1, 1, 2, 3); + int valueToRemove = 1; + + // when + removeWithRemoveIf(list, valueToRemove); + + // then + assertThat(list).isEqualTo(list(2, 3)); + } + +}