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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..."
 
Don't get me started about those stupid light bulbs.
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