diff --git a/core-java-modules/core-java-collections-6/README.md b/core-java-modules/core-java-collections-6/README.md index b5f1adbf48..736e91f110 100644 --- a/core-java-modules/core-java-collections-6/README.md +++ b/core-java-modules/core-java-collections-6/README.md @@ -3,3 +3,5 @@ ## Core Java Collections Cookbooks and Examples ### Relevant Articles: + +- More articles: [[<-- prev]](/core-java-modules/core-java-collections-5) diff --git a/core-java-modules/core-java-collections-6/src/test/java/com/baeldung/iteratorvsforeach/IteratorVsForeachUnitTest.java b/core-java-modules/core-java-collections-6/src/test/java/com/baeldung/iteratorvsforeach/IteratorVsForeachUnitTest.java new file mode 100644 index 0000000000..ca9390a3ee --- /dev/null +++ b/core-java-modules/core-java-collections-6/src/test/java/com/baeldung/iteratorvsforeach/IteratorVsForeachUnitTest.java @@ -0,0 +1,64 @@ +package com.baeldung.iteratorvsforeach; + +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertIterableEquals; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.Iterator; +import java.util.List; +import java.util.stream.Stream; + +import org.junit.jupiter.api.Test; +import org.junit.jupiter.params.ParameterizedTest; +import org.junit.jupiter.params.provider.Arguments; +import org.junit.jupiter.params.provider.MethodSource; + +class IteratorVsForeachUnitTest { + + private static Stream listProvider() { + return Stream.of(Arguments.of(List.of("String1", "String2", "unwanted"), List.of("String1", "String2"))); + } + + @Test + public void givenEmptyCollection_whenUsingForEach_thenNoElementsAreIterated() { + List names = Collections.emptyList(); + StringBuilder stringBuilder = new StringBuilder(); + names.forEach(stringBuilder::append); + assertEquals("", stringBuilder.toString()); + } + + @ParameterizedTest + @MethodSource("listProvider") + public void givenCollectionWithElements_whenRemovingElementDuringForEachIteration_thenElementIsRemoved(List input, List expected) { + List mutableList = new ArrayList<>(input); + // Separate collection for items to be removed + List toRemove = new ArrayList<>(); + + // Using forEach to identify items to remove + input.forEach(item -> { + if (item.equals("unwanted")) { + toRemove.add(item); + } + }); + + // Removing the identified items from the original list + mutableList.removeAll(toRemove); + assertIterableEquals(expected, mutableList); + } + + @ParameterizedTest + @MethodSource("listProvider") + public void givenCollectionWithElements_whenRemovingElementDuringIteratorIteration_thenElementIsRemoved(List input, List expected) { + List mutableList = new ArrayList<>(input); + Iterator it = mutableList.iterator(); + while (it.hasNext()) { + String item = it.next(); + if (item.equals("unwanted")) { + it.remove(); // Safely remove item + } + } + assertIterableEquals(expected, mutableList); + } + +}