baeldung-articles : BAEL-7500 (#16084)

* baeldung-articles : BAEL-7500

Adding elements to a collection during iteration.

* I modify the ListIterationUnitTest.java

core-java-modules/core-java-collections/src/test/java/com/baeldung/listiteration/ListIterationUnitTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.listiteration;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertIterableEquals;
+
+public class ListIterationUnitTest {
+
+    List<String> programmingLanguages = new ArrayList<>(List.of("Java", "Python", "C++"));
+    List<Integer> numbers = new ArrayList<>(List.of(1, 2, 3));
+
+   @Test
+    public void givenStringList_whenAddElementWithListIterator_thenModifiedList() {
+        ListIterator<String> listIterator = programmingLanguages.listIterator();
+        while (listIterator.hasNext()) {
+            String language = listIterator.next();
+            if (language.equals("Python")) {
+                listIterator.add("JavaScript");
+            }
+        }
+
+        assertIterableEquals(Arrays.asList("Java", "Python", "JavaScript", "C++"), programmingLanguages);
+    }
+
+    @Test
+    public void givenNumericalList_whenMultiplyElementWithListIterator_thenModifiedList() {
+        ListIterator<Integer> listIterator = numbers.listIterator();
+        while (listIterator.hasNext()) {
+            int num = listIterator.next();
+            if (num == 2) {
+                listIterator.add(num * 10);
+            }
+        }
+        assertIterableEquals(Arrays.asList(1, 2, 20, 3), numbers);
+    }
+
+    @Test
+    public void givenStringList_whenAddElementWithEnhancedForLoopAndCopy_thenModifiedList() {
+        List<String> copyOfWords = new ArrayList<>(programmingLanguages);
+        for (String word : copyOfWords) {
+            programmingLanguages.add(word.toUpperCase()); // Modified: Convert to uppercase
+        }
+        assertIterableEquals(Arrays.asList("Java", "Python", "C++", "JAVA", "PYTHON", "C++"), programmingLanguages);
+    }
+
+    @Test
+    public void givenNumericalList_whenMultiplyElementWithEnhancedForLoopAndCopy_thenModifiedList() {
+        List<Integer> copyOfNumbers = new ArrayList<>(numbers);
+        for (int num : copyOfNumbers) {
+            numbers.add(num * 2);
+        }
+        assertIterableEquals(Arrays.asList(1, 2, 3, 2, 4, 6), numbers);
+    }
+
+    @Test
+    public void givenStringList_whenConvertToUpperCaseWithJava8Stream_thenModifiedList() {
+        programmingLanguages = programmingLanguages.stream().map(String::toUpperCase).collect(Collectors.toList());
+        assertIterableEquals(Arrays.asList("JAVA", "PYTHON", "C++"), programmingLanguages);
+    }
+
+    @Test
+    public void givenNumericalList_whenMultiplyByThreeWithJava8Stream_thenModifiedList() {
+        numbers = numbers.stream().map(num -> num * 3).collect(Collectors.toList());
+        assertIterableEquals(Arrays.asList(3, 6, 9), numbers);
+    }
+
+}