CODEWITHSUNDEEP
javaarrays2d
MHR
MHR

Reputation: 53

Is there any shorter code or easier way to add elements into multiple arrays of different sizes?

This is my codes where I am trying to add elements randomly. Is there an way to add elements using while loops, for loops or for each loops in Java? 

package arrays_into_2d_array;

import java.util.*;

public class Arrays2DArray {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

    Random random = new Random();

    int [] arr1 = new int[50];
    for(int i = 0; i < arr1.length; i++){
        arr1[i] = 1+random.nextInt(5);
    }
    int [] arr2 = new int[100];
        for(int i = 0; i < arr2.length; i++){
        arr2[i] = 1+random.nextInt(5);
    }
    int [] arr3 = new int[200];
        for(int i = 0; i < arr3.length; i++){
        arr3[i] = 1+random.nextInt(5);
    }
    int [] arr4 = new int[400];
        for(int i = 0; i < arr4.length; i++){
        arr4[i] = 1+random.nextInt(5);
    }
    int [] arr5 = new int[800];
        for(int i = 0; i < arr5.length; i++){
        arr5[i] = 1+random.nextInt(5);
    }
    int [] arr6 = new int[1600];
        for(int i = 0; i < arr6.length; i++){
        arr6[i] = 1+random.nextInt(5);
    }
    int [] arr7 = new int[3200];
        for(int i = 0; i < arr7.length; i++){
        arr7[i] = 1+random.nextInt(5);
    }
    int [] arr8 = new int[6400];
        for(int i = 0; i < arr8.length; i++){
        arr8[i] = 1+random.nextInt(5);
    }
    int [] arr9 = new int[12800];
        for(int i = 0; i < arr9.length; i++){
        arr9[i] = 1+random.nextInt(5);
    }
    int [] arr10 = new int[25600];
        for(int i = 0; i < arr10.length; i++){
        arr10[i] = 1+random.nextInt(5);
    }


    int [][] arr2D = {arr1, arr2, arr3, arr4, arr5, arr6, arr7, arr8, arr9, arr10};

    for(int i = 0; i < arr2D.length; i++){
        System.out.println("Index = "+i+" of 2D array has = "+arr2D[i].length+" number of elements.");
    }

    }

}

Any help will be appreciated.

Upvotes: 0

Views: 41

Answers (3)

fabian
fabian

Reputation: 82461

Not exactly a loop, but the java 8 version using the stream API is definetly short:

int[][] arr2D = IntStream.range(0, 10).map(i -> 50 << i) // stream of sizes
                         .mapToObj(size -> IntStream.generate(() -> random.nextInt(5) + 1).limit(size).toArray()) // stream of arrays with given sizes
                         .toArray(int[][]::new); // combine arrays

Upvotes: 0

randers
randers

Reputation: 5146

Of course. What you are looking for is a method.

You would declare a method which accepts a int[] and a Random instance and performs the loop:

public static void assignRandomValues(int[] array, Random random)
{
    for (int i = 0; i < array.length; i++)
    {
        array[i] = 1 + random.nextInt(5);
    }
}

Then you would turn your code into this:

int[] arr1 = new int[50];
assignRandomValues(arr1, random);

...and so on.

Upvotes: 0

MikeCAT
MikeCAT

Reputation: 75062

You are writing too many codes that are almost same, so you should use loop.

package arrays_into_2d_array;

import java.util.*;

public class Arrays2DArray {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        Random random = new Random();
        int [] sizes = {50, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 25600};
        int [][] arr2D = new int[sizes.length][];
        for(int i = 0; i < arr2D.length; i++){
            arr2D[i] = new int[sizes[i]];
            for(int j = 0; j < arr2D[i].length; j++){
                arr2D[i][j] = 1+random.nextInt(5);
            }
        }

        for(int i = 0; i < arr2D.length; i++){
            System.out.println("Index = "+i+" of 2D array has = "+arr2D[i].length+" number of elements.");
        }

    }

}

Upvotes: 2

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