Sohaib Sohaib - 5 months ago 10
Java Question

error on 2D array

this is a 2D array that took the value from user put it's gave me NullPointerException error!!
btw I'm beginner so if you can make it more detailed. thanks

public static void main(String[] args) {
java.util.Scanner scan = new Scanner(System.in);
int[][] matrix = null;
System.out.println("Enter " + matrix.length + " rows and " +
matrix[0].length + " columns: ");

for (int row = 0; row < matrix.length; row++) {

for (int column = 0; column < matrix[row].length; column++) {

matrix[row][column] = scan.nextInt();

}
}
}


error

Exception in thread "main" java.lang.NullPointerException

Answer

you should to define the size of your matrix like that for exemple:

public static void main(String[] args) {
    java.util.Scanner scan = new Scanner(System.in);
    int[][] matrix = new int[5][1];
    System.out.println("Enter " + matrix.length + " rows and "
            + matrix[0].length + " columns: ");

    for (int row = 0; row < matrix.length; row++) {

        for (int column = 0; column < matrix[row].length; column++) {

            matrix[row][column] = scan.nextInt();

        }
    }
}