Java: Reversing a string word by word

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args)
   {
 
        String str, str2="";

      Scanner in = new Scanner(System.in);

        str=in.nextLine();
        System.out.println(str);
      String[] str1=str.split(" ");
        for(int i=str1.length-1;i>=0;i--)
            str2=str2 + str1[i] + " ";
      System.out.println(str2);

   }
}