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Hello Members,

I am trying to multiply two matrices using multithreading. I get a NullPointerException on the line that is commented in Bold.

Following is the entire code. Any input is much appreciated.

```
import java.lang.*;
import java.io.*;
public class Matrix_Mult extends Thread
{
static int a[][]; static int b[][]; static int c[][];
static int n = 3;
int row;
Matrix_Mult(int p)
{
row =p;
this.start();
}
public void run()
{
int i, j;
for (i=0; i<n; i++)
{
for (j=0; j<n; j++)
{
c [row][i] += a[row][j] * b[j][i]; [B]//[B][B]NullPointerException on this line[/B][/B][/B]
}
}
}
public static void main(String args[])
{
int a [][] = { {1,2,3}, {4,5,6}, {7,8,9}};
int b [][] = { {1,2,3}, {4,5,6}, {7,8,9}};
int c [][] = { {0,0,0}, {0,0,0}, {0,0,0}};
Matrix_Mult y [] = new Matrix_Mult[n];
for (k=0; k<n; k++)
{
y[k] = new Matrix_Mult(k);
}
try {
for (i=0; i<n; i++)
{
y[i].join();
}
}
catch (Exception e)
{}
}
}
```

*Edited 6 Years Ago by sciprog1*: n/a