Lets say this is the array i want to shuffle randomly, what would be the most efficient way to do so? How could i populate this kind of array with three specific values (0, 0.5, 1) but in random order each time i start the program?

Can i use something like " a[i][j] = rand.nextDouble() " ?

Double a[][] = {{0, 1, 0.5, 0.5, 0.5}, {0, 1, 0, 1, 1}, {0.5, 1, 0.5, 0.5, 0}, {0, 0.5, 0, 0.5, 0}, {1, 1, 0.5, 1, 1}, {0, 0, 0, 0.5, 0.5}, {0, 0.5, 0, 0, 1}};

I tried generating this array witha[i][j] = (rand..nextDouble() * (1-0)) 0.5;but it turns out values like 1.2 and 0.3 etc, is there a way to increase random values by 0.5 only? so that they can be in range from 0-1?

Thank you!

CodePudding user response：

Generate an integer between 0 and 2 (inclusive) – 0 and 3 (exclusive), then divide by 2. This will give you 0.5 steps (1/2 = 0.5).

To initialize your array, create a function to return a random array of 5 values. Then call this method 5 times and assign it to each index of your top-level array.

CodePudding user response：

Rather than trying to generate a new random number you can add the required numbers into an array and generate a random index to choose the numbers.

import java.lang.Math;

class MainRun {
    public static void main(String[] args) {
        double arr[][] = new double[5][7];
        double num[] = { 0, 0.5, 1, 1.5 };

        for (int i = 0; i < 5; i  ) {
            for (int j = 0; j < 7; j  ) {
                int rand = (int) (Math.floor(Math.random() * 4));
                arr[i][j] = num[rand];
            }
        }
    }
}

Output :

0.0 0.0 0.0 0.5 1.5 0.5 0.0 
0.0 0.5 0.5 1.5 0.5 1.5 1.0
1.5 0.5 1.5 1.0 1.5 0.0 1.0
1.0 0.0 1.5 0.5 0.0 1.0 1.5 
0.5 1.5 0.0 1.5 0.5 0.0 0.0 

Printing the 2d Array ^