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Merged
pivovarit merged 2 commits into from
Jul 31, 2018
Merged

Bael 2023 #4851

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9d0e786
bael-2023: removing all occurrences of a value from a list
fanatixan Jul 24, 2018
bfa4d29
adjusting examples to match the article
fanatixan Jul 29, 2018
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111 changes: 111 additions & 0 deletions core-java-8/src/main/java/com/baeldung/list/RemoveAll.java
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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<Integer> list, int element) {
while (list.contains(element)) {
list.remove(element);
}
}

static void removeWithWhileLoopNonPrimitiveElement(List<Integer> list, Integer element) {
while (list.contains(element)) {
list.remove(element);
}
}

static void removeWithWhileLoopStoringFirstOccurrenceIndex(List<Integer> list, Integer element) {
int index;
while ((index = list.indexOf(element)) >= 0) {
list.remove(index);
}
}

static void removeWithCallingRemoveUntilModifies(List<Integer> list, Integer element) {
while (list.remove(element))
;
}

static void removeWithStandardForLoopUsingIndex(List<Integer> 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<Integer> 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<Integer> 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<Integer> list, int element) {
for (Integer number : list) {
if (Objects.equals(number, element)) {
list.remove(number);
}
}
}

static void removeWithIterator(List<Integer> list, int element) {
for (Iterator<Integer> i = list.iterator(); i.hasNext();) {
Integer number = i.next();
if (Objects.equals(number, element)) {
i.remove();
}
}
}

static List<Integer> removeWithCollectingAndReturningRemainingElements(List<Integer> list, int element) {
List<Integer> remainingElements = new ArrayList<>();
for (Integer number : list) {
if (!Objects.equals(number, element)) {
remainingElements.add(number);
}
}
return remainingElements;
}

static void removeWithCollectingRemainingElementsAndAddingToOriginalList(List<Integer> list, int element) {
List<Integer> remainingElements = new ArrayList<>();
for (Integer number : list) {
if (!Objects.equals(number, element)) {
remainingElements.add(number);
}
}

list.clear();
list.addAll(remainingElements);
}

static List<Integer> removeWithStreamFilter(List<Integer> list, Integer element) {
return list.stream()
.filter(e -> !Objects.equals(e, element))
.collect(Collectors.toList());
}

static void removeWithRemoveIf(List<Integer> list, Integer element) {
list.removeIf(n -> Objects.equals(n, element));
}

}
208 changes: 208 additions & 0 deletions core-java-8/src/test/java/com/baeldung/list/RemoveAllUnitTest.java
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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<Integer> list(Integer... elements) {
return new ArrayList<>(Arrays.asList(elements));
}

@Test
public void givenAList_whenRemovingElementsWithWhileLoopUsingPrimitiveElement_thenTheResultCorrect() {
// given
List<Integer> list = list(1, 2, 3);
int valueToRemove = 1;

// when
assertThatThrownBy(() -> removeWithWhileLoopPrimitiveElement(list, valueToRemove))
.isInstanceOf(IndexOutOfBoundsException.class);
}

@Test
public void givenAList_whenRemovingElementsWithWhileLoopUsingNonPrimitiveElement_thenTheResultCorrect() {
// given
List<Integer> 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<Integer> 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<Integer> 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<Integer> 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<Integer> 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<Integer> 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<Integer> 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<Integer> 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<Integer> 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<Integer> list = list(1, 1, 2, 3);
int valueToRemove = 1;

// when
List<Integer> result = removeWithCollectingAndReturningRemainingElements(list, valueToRemove);

// then
assertThat(result).isEqualTo(list(2, 3));
}

@Test
public void givenAList_whenRemovingElementsWithCollectingRemainingAndAddingToOriginalList_thenTheResultIsCorrect() {
// given
List<Integer> 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<Integer> list = list(1, 1, 2, 3);
int valueToRemove = 1;

// when
List<Integer> result = removeWithStreamFilter(list, valueToRemove);

// then
assertThat(result).isEqualTo(list(2, 3));
}

@Test
public void givenAList_whenRemovingElementsWithCallingRemoveIf_thenTheResultIsCorrect() {
// given
List<Integer> list = list(1, 1, 2, 3);
int valueToRemove = 1;

// when
removeWithRemoveIf(list, valueToRemove);

// then
assertThat(list).isEqualTo(list(2, 3));
}

}