Creating and initialising a 2D Array in Java

Question

I haven't used 2D Arrays before so apologies for any 'obvious statements'. I want to create a 2D Array for a 15 by 20 'table' and want the following to be applied:

I want each row to be a separate Array.
I want each row to have random 0's and 1's generated

The code I have created creates the 15 x 20 table but not sure if each row is an Array and can't figure out how to put random 0's and 1's. Help would be appreciated! Thanks!

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

Reut Sharabani · Accepted Answer · 2014-02-07 18:59:50Z

2

Like this?

int cols = 15;
int rows = 20;

Random rand = new Random();

int[][] myArray = new int[rows][cols];

for (int i=0; i < myArray.length; i++) {
    for (int j=0; j < myArray[i].length; j++) {
        myArray[i][j] = rand.nextInt(2);
        System.out.print(" " + myArray[i][j]);
    }
    System.out.println("");
}

2 Comments

user786 Over a year ago

Oh that was simple. Cheers for the help!

user786 Over a year ago

I managed to change it so it showed random number from 1 to 10, which I want. But I want to know how do I limit the number of times as number appear, to 4??

Anirban Nag 'tintinmj' · Accepted Answer · 2014-02-07 18:59:24Z

1

Use nextInt method.

myArray[i][j] = rand.nextInt(2); // we are using 2 cause nextInt generates random number between 0 to 2 exclusive.

answered Feb 7, 2014 at 18:59

Anirban Nag 'tintinmj'

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