Java Reverse String

import java.util.*;
public class ReverseString{
    public static void main(String[]args){
        Scanner input=new Scanner(System.in);
        System.out.print("Enter string: ");
        String str=input.nextLine();
        System.out.print("Enter word: ");
        String word=input.next();

        String repword="";
        String arr[]=str.split(" ");
        for(int i=0;i<arr.length;i++){
           if(arr[i].equals(word)){
            repword= new StringBuffer(word).reverse().toString();
           }
        }
        String reverse=str.replace(word,repword);
        System.out.println(reverse);
    }
}