Merge pull request #15073 from Neetika23/stringIterationCode

String iteration code

core-java-modules/core-java-strings/src/main/java/com/baeldung/stringIterator/StringIterator.java

@@ -0,0 +1,42 @@
+package com.baeldung.stringIterator;
+
+import java.text.*; 
+import java.util.*;
+
+public class StringIterator {
+
+    public static String javaCharArray(String str){
+        StringBuilder result = new StringBuilder();
+        for (char c : str.toCharArray()) { 
+            result.append(c);
+        }
+        return result.toString();
+    }
+
+    public static String javaforLoop(String str) {
+        StringBuilder result = new StringBuilder();
+        for (int i = 0; i < str.length(); i++) {
+            char c = str.charAt(i);
+            result.append(c);
+        }
+        return result.toString();
+    }
+
+    public static String java8forEach(String str){
+        StringBuilder result = new StringBuilder();
+        str.chars().forEach(name -> {
+            result.append((char) name);
+        });
+        return result.toString();
+    }
+
+    public static String javaCharacterIterator(String str){
+        StringBuilder result = new StringBuilder();
+        CharacterIterator it = new StringCharacterIterator(str);  
+        while (it.current() != CharacterIterator.DONE) { 
+            result.append(it.current()); 
+            it.next(); 
+        }
+        return result.toString();
+    }
+}

core-java-modules/core-java-strings/src/test/java/com/baeldung/stringIterator/StringIteratorTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.stringIterator;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class StringIteratorTest {
+  
+    @Test
+    public void whenUseCharArrayMethod_thenIterate() {
+        String input = "Hello, Baeldung!";
+        String expectedOutput = "Hello, Baeldung!";
+        String result = StringIterator.javaCharArray(input);
+        assertEquals(expectedOutput, result);
+    }
+  
+    @Test
+    public void whenUseJavaForLoop_thenIterate() {
+        String input = "Hello, Baeldung!";
+        String expectedOutput = "Hello, Baeldung!";
+        String result = StringIterator.javaForLoop(input);
+        assertEquals(expectedOutput, result);
+    }
+  
+    @Test
+    public void whenUseForEachMethod_thenIterate() {
+        String input = "Hello, Baeldung!";
+        String expectedOutput = "Hello, Baeldung!";
+        String result = StringIterator.java8ForEach(input);
+        assertEquals(expectedOutput, result);
+    }
+  
+    @Test
+    public void whenUseCharacterIterator_thenIterate() {
+        String input = "Hello, Baeldung!";
+        String expectedOutput = "Hello, Baeldung!";
+        String result = StringIterator.javaCharacterIterator(input);
+        assertEquals(expectedOutput, result);
+    }
+}