Added Character Array method (#5965)

* Added the code of Replace char in a string at specific index

* added test cases

* Renamed the Test class name end with UnitTest

* Renamed the Test class name end with UnitTest

* Renamed the Test class name end with UnitTest

* Replaced README with the upstream repo

* Added Char Array Method

java-strings/src/main/java/com/baeldung/string/ReplaceCharacterInString.java

@@ -1,11 +1,19 @@
 package com.baeldung.string;
 
 public class ReplaceCharacterInString {
+
     public String replaceCharSubstring(String str, char ch, int index) {
         String myString = str.substring(0, index) + ch + str.substring(index + 1);
         return myString;
     }
 
+    public String replaceCharUsingCharArray(String str, char ch, int index) {
+        char[] chars = str.toCharArray();
+        chars[index] = ch;
+        return String.valueOf(chars);
+    }
+
+
     public String replaceCharStringBuilder(String str, char ch, int index) {
         StringBuilder myString = new StringBuilder(str);
         myString.setCharAt(index, ch);

java-strings/src/test/java/com/baeldung/string/ReplaceCharInStringUnitTest.java

@@ -1,6 +1,7 @@
 package com.baeldung.string;
 
 import org.junit.Test;
+
 import static org.junit.Assert.*;
 
 public class ReplaceCharInStringUnitTest {
@@ -11,6 +12,11 @@ public class ReplaceCharInStringUnitTest {
         assertEquals("abcme", characterInString.replaceCharSubstring("abcde", 'm', 3));
     }
 
+    @Test
+    public void whenReplaceCharAtIndexUsingCharArray_thenSuccess() {
+        assertEquals("abcme", characterInString.replaceCharUsingCharArray("abcde", 'm', 3));
+    }
+
     @Test
     public void whenReplaceCharAtIndexUsingStringBuilder_thenSuccess() {
         assertEquals("abcme", characterInString.replaceCharStringBuilder("abcde", 'm', 3));