CODEWITHSUNDEEP
javaeclipse
rakesh kumar
rakesh kumar

Reputation: 97

Getting error in the following Java program. Why?

I am getting error as "Exception in thread "main" java.lang.NullPointerException at Pascal.main(Pascal.java:8)"

public class Pascal {
    public static void main(String args[]){

    int rows,i,j,k;
    rows=Integer.parseInt(args[0]);
    double pas[][]= new double[rows][];
    pas[0][0]=1; //the line of error

    for (i=1;i<=rows;i++){
        for (j=1;j<=i;j++){
            pas[i-1][j-1]=pas[i-2][j-2]+pas[i-2][j-1];
        }
    }

    for(i=0;i<rows;i++){
        for(j=0;j<=i;j++){
            System.out.print(pas[i][j]);
        }
        System.out.println("");
    }
}

}

Why I am getting error on line: pas[0][0]=1;

Upvotes: 0

Views: 57

Answers (4)

Krutik Jayswal
Krutik Jayswal

Reputation: 3175

package com.survey.ui;

class demo {
public static void main(String args[]){

    int rows,i,j,k;
    rows=Integer.parseInt(args[0]);
    double pas[][]= new double[rows][Integer.parseInt(args[0])];
    pas[0][0]=1;

    for (i=2;i<=rows;i++){
        for (j=2;j<=i;j++){
            pas[i-1][j-1]=pas[i-2][j-2]+pas[i-2][j-1];
        }
    }


    for(i=0;i<rows;i++){
        for(j=0;j<=i;j++){
            System.out.print(pas[i][j]);
        }
        System.out.println("");
    }
}
}

I am not aware of your business logic but above will run.

Upvotes: 0

atish shimpi
atish shimpi

Reputation: 5023

In two dimensional array, you have to specify the column size also. 

double pas[][]= new double[rows][cols];

Upvotes: 0

Peter
Peter

Reputation: 5798

you didnt initialise your array properly

double pas[][]= new double[rows][here columns are missing];

Upvotes: 1

Eran
Eran

Reputation: 393801

You only initialize the outer array with double pas[][]= new double[rows][];, so pas[0] is still null, and pas[0][0] gives NullPointerException.

Change

pas[0][0]=1;

to

pas[0] = new double[1];
pas[0][0]=1;

You also have to call pas[i] = new double[some-length]; for the other rows.

Upvotes: 2

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