Answers for "java program to reverse a string without using string inbuilt function"

Reverse a string in java

// reverse a string using reverse() method of StringBuilder class
class ReverseUsingReverseMethod
{
   public static void main(String[] args)
   {
      String str = "Hello world Java";
      StringBuilder sb = new StringBuilder();
      // append string to StringBuilder
      sb.append(str);
      sb = sb.reverse();
      // printing reversed String
      System.out.println(sb);
   }
}

reverse a string in java

// Not the best way i know but i wanted to challenge myself to do it this way so :)
public static String reverse(String str) {
  char[] oldCharArray = str.toCharArray();
  char[] newCharArray= new char[oldCharArray.length];
  int currentChar = oldCharArray.length-1;
  for (char c : oldCharArray) {
    newCharArray[currentChar] = c;
    currentChar--;
  }
  return new String(newCharArray);
}