Why does this give Null Pointer Exception

[sanpraveen Kumar]

import java.io.*;

public class B //1
{
public static void main(String arg[]) //2
{
int [][]a=new int[2][];

for(int k=0;k<2;k++)
{a[0][k]=0;}
for(int k=0;k<3;k++)
{a[1][k]=k;}

}
}

[James Carman]

Because you're not initializing the int[] elements of your int[][].

[fred rosenberger]

In other words, you've created a REFERENCE to a 2d array, but you don't ever create the elements in it.

it's like saying "Get an envelope. now, take the letter out of the envelope and go to page 3..."