where is this code is wrong

package javaapplication3;
public class thread
{
public static void main(String[] args)
    {
    int a[][]={{3,4,2,9},{2,3,4,5},{2,2,3,4}};
    int b[][]={{6,7,8,3},{4,2,1,3},{8,3,5,6}};
    int sum[][]=new int[4][4];
    System.out.println("First Matrix A is:-");
    for (int i=0;i<=3;i++)
    {
        for (int j=0;j<=3;j++)
        {
            System.out.print(" "+a[i]);
        }
        System.out.println();
    }
    System.out.println("First Matrix B is:-");
    for (int i=0;i<=3;i++)
    {
        for (int j=0;j<=3;j++)
        {
            System.out.print(" "+b[j]);
        }
        System.out.println();
    }
    }

}