Z pattern in 2D matrics

import java.util.*;

public class Main {
    public static void main(String[] args) {
      int a[][]={{1,2,3},{4,5,6},{7,8,9}};
      for(int i=0;i<a.length;i++){
        for(int j=0;j<a.length;j++){
      
        }
      }
      for(int i=0;i<a.length;i++){
        for(int j=0;j<a.length;j++){
          if((i+j)==a.length-1){
            System.out.print(a[i][j]+" ");
          }else if(i==0){
            System.out.print(a[i][j]+" ");
          }else if(i==2){
            System.out.print(a[i][j]+" ");
          }else{
            System.out.print("  ");
          }
        }
        System.out.println();
      }
  }
}