Java Initialise Multidimensional Array with Random Integers

Question

I am looking to initialise a multidimensional array with random numbers between 0 and 100 (inclusive). I am able to create the multidimensional array with empty values at each field and am then able to add 100 random numbers into the available positions.

However, I would like to know if there is a way of initialising the multidimensional array with random natural integers. For example, I am looking to do it a little something like this:

double[][] array = new double[][] {{0, 1, 2} , {1, 0, 3} , {2, 3, 0}};

Is this possible? I'm thinking something along the lines of:

double[][] array = new double[][] {{random values go here},{random values go here}};

Any suggestions?

Thank you all for taking the time to read.

Mick

Are you looking to generate the random numbers just once, or should it be a new set of random numbers on every run? — Kevin K
– Kevin K, Commented Mar 8, 2011 at 23:42
Hi Kevin, I am looking to generate a new set of random numbers on each run. — Mus
– Mus, Commented Mar 8, 2011 at 23:46

OscarRyz · Accepted Answer · 2011-03-08 23:51:13Z

3

Create the array and then initialize it in a for loop. Random.nextInt(n) gives you what you need.

Here's a sample code with three different runs.

import java.util.*;
class Init { 
    public static void main( String ... args ) { 

        Random random = new Random();

        double[][] array = new double[10][10];

        for( int i = 0 ; i < array.length ; i++ ) { 
           for ( int j = 0 ; j < array[i].length ; j++ ) { 
              array[i][j] = random.nextInt(101);
           }
        }

        for( double[] a : array ) { 
            System.out.println( Arrays.toString( a ));
        }
    }
}

Output:

C:\Users\oreyes\langs\java>java Init
[2.0, 92.0, 31.0, 98.0, 3.0, 5.0, 57.0, 41.0, 29.0, 89.0]
[54.0, 57.0, 68.0, 92.0, 11.0, 20.0, 14.0, 58.0, 84.0, 23.0]
[48.0, 14.0, 9.0, 33.0, 9.0, 27.0, 74.0, 34.0, 85.0, 91.0]
[51.0, 87.0, 2.0, 96.0, 52.0, 81.0, 91.0, 95.0, 19.0, 56.0]
[15.0, 90.0, 9.0, 85.0, 51.0, 23.0, 35.0, 21.0, 78.0, 14.0]
[23.0, 20.0, 57.0, 94.0, 69.0, 99.0, 90.0, 78.0, 61.0, 38.0]
[35.0, 61.0, 81.0, 72.0, 3.0, 93.0, 20.0, 96.0, 9.0, 35.0]
[90.0, 100.0, 98.0, 14.0, 95.0, 75.0, 96.0, 8.0, 87.0, 25.0]
[14.0, 41.0, 27.0, 57.0, 32.0, 37.0, 69.0, 61.0, 5.0, 42.0]
[57.0, 0.0, 85.0, 28.0, 78.0, 47.0, 89.0, 54.0, 50.0, 59.0]

C:\Users\oreyes\langs\java>java Init
[3.0, 27.0, 37.0, 31.0, 52.0, 19.0, 63.0, 81.0, 88.0, 12.0]
[80.0, 27.0, 7.0, 55.0, 21.0, 100.0, 73.0, 62.0, 9.0, 91.0]
[85.0, 50.0, 66.0, 27.0, 63.0, 44.0, 0.0, 37.0, 93.0, 82.0]
[73.0, 57.0, 4.0, 80.0, 5.0, 51.0, 63.0, 13.0, 97.0, 11.0]
[87.0, 62.0, 20.0, 14.0, 44.0, 77.0, 71.0, 42.0, 27.0, 82.0]
[37.0, 32.0, 96.0, 95.0, 45.0, 8.0, 11.0, 38.0, 61.0, 6.0]
[34.0, 67.0, 84.0, 50.0, 38.0, 64.0, 50.0, 51.0, 50.0, 47.0]
[79.0, 31.0, 54.0, 37.0, 27.0, 54.0, 57.0, 30.0, 77.0, 36.0]
[74.0, 20.0, 98.0, 37.0, 8.0, 17.0, 18.0, 1.0, 29.0, 56.0]
[21.0, 4.0, 33.0, 87.0, 4.0, 76.0, 65.0, 62.0, 76.0, 96.0]

C:\Users\oreyes\langs\java>java Init
[17.0, 3.0, 78.0, 32.0, 99.0, 76.0, 94.0, 93.0, 31.0, 55.0]
[4.0, 25.0, 63.0, 68.0, 58.0, 39.0, 7.0, 55.0, 73.0, 86.0]
[96.0, 89.0, 6.0, 100.0, 20.0, 58.0, 100.0, 91.0, 35.0, 46.0]
[3.0, 16.0, 88.0, 82.0, 85.0, 35.0, 0.0, 1.0, 91.0, 78.0]
[3.0, 33.0, 77.0, 10.0, 69.0, 60.0, 75.0, 58.0, 8.0, 31.0]
[72.0, 36.0, 2.0, 19.0, 39.0, 15.0, 5.0, 74.0, 16.0, 28.0]
[48.0, 71.0, 38.0, 17.0, 37.0, 34.0, 80.0, 98.0, 16.0, 42.0]
[66.0, 74.0, 96.0, 80.0, 75.0, 7.0, 14.0, 46.0, 63.0, 56.0]
[4.0, 15.0, 8.0, 93.0, 58.0, 21.0, 81.0, 100.0, 2.0, 44.0]
[20.0, 71.0, 41.0, 43.0, 83.0, 7.0, 60.0, 28.0, 99.0, 42.0]

edited Mar 8, 2011 at 23:51

answered Mar 8, 2011 at 23:46

OscarRyz

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3 Comments

Mus Over a year ago

Thank you so much for this wonderful answer; unfortunately, I encounter an error when attempting this. The error flags up on the following line: array[i][j] = random.nextInt(101); It highlights/underlines 'nextInt' and displays the following message: "The method nextInt(int) is undefined for the type Integer". What could the problem be here? Thank you, OscarRyz.

OscarRyz Over a year ago

You've defined random as Integer , declare it as Random as in : Random random = new Random()

Mus Over a year ago

I have tried that and still no luck unfortunately...could there be an error elsewhere in my project that eclipse has not detected?

Oliver Charlesworth · Accepted Answer · 2011-03-08 23:38:47Z

1

Will Random.nextInt() do what you want?

answered Mar 8, 2011 at 23:38

Oliver Charlesworth

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1 Comment

Mus Over a year ago

Thank you guys, but unfortunately this has not worked. May I ask how I would implement the Random.nextInt()/Random.nextInt(101) method into my 3D array? Thanks.

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