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Why does this give Null Pointer Exception

 
Greenhorn
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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;}

}
}
 
Ranch Hand
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Because you're not initializing the int[] elements of your int[][].
 
lowercase baba
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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..."
 
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