Leer 2 matrices e intercambiar valores

import java.util.*;
public class problema1{
   public static void main (){
       int a[][] = new int[3][3];
       int b[][] = new int[3][3];
       int x[][] = new int[3][3];
       int i,j;
       Scanner teclado = new Scanner (System.in);
       System.out.println("Escribe los valores de la matriz A"); 
       for (i=0; i<3;i++){
           for (j=0; j<3;j++){
               System.out.print( i +","+ j +": " );
               a [i][j] = teclado.nextInt();
            }
        }
          System.out.println("Matriz A completa");   
          System.out.println("");
        System.out.println("Escribe los valores de la matriz B");
          for (i=0; i<3;i++){
           for (j=0; j<3;j++){
               System.out.print(i +","+ j+ ": ");
               b [i][j] = teclado.nextInt();
            }
        }
              
        for (i=0; i<3;i++){
           for (j=0; j<3;j++){
        x [i][j] = b [i][j];
        b [i][j] = a [i][j];
        a [i][j] = x [i][j];
           
             }
           
        }  
   }
}