How to store and return the array with the squared result from array in method parameters

Question

public class Practise
{
    public static void main(String[] args)
    {
        double[] array = {1.0,2.0,2.0,4.0};
        System.out.println(square(array));
    }
    public static double[] square (double[] a)
    {
        double [] squared = new double[a.length];
        for (int i = 0; i <a.length ; i++)  {
            squared[i] = a[i] * a[i];
        }
        return squared;
    }

I'm trying to update squared array with the result of a array's values squared and then return it but I'm keep getting an [D@1540e19d error , sorry if it is a easy question I am a student just started learning java!`

Possible duplicate of [What's the simplest way to print a Java array?](https://stackoverflow.com/questions/409784/whats-the-simplest-way-to-print-a-java-array) — Tom, May 29 '17 at 15:22

score 0 · Answer 1 · answered May 29 '17 at 15:26

You are printing the array object reference, you should print each cell of your array, try:

public class Practise
{
    public static void main(String[] args)
    {
        double[] array = {1.0,2.0,2.0,4.0};
        double[] result = square(array);

        for(int i = 0; i < result.length; i++)
        {
          System.out.println("Square of " + array[i] + " is: " + result[i]);
        }

    }


    public static double[] square (double[] a)
    {
        double [] squared = new double[a.length];
        for (int i = 0; i <a.length ; i++)  {
            squared[i] = a[i] * a[i];
        }
        return squared;
    }
}

Thanks a lot that really helped - makes a lot sense doing it this way ! — Michael Wright, May 29 '17 at 15:33

Vasyl Lyashkevych · Answer 2 · 2017-05-29T15:41:07.430

You need to make some modifications in your code: For case 1:

public class Practise {

    public static void main(String[] args) {
        double[] array = {1.0, 2.0, 2.0, 4.0};
        array = square(array); //to get new array from method
        for(int i=0; i<array.length; i++)
            System.out.println(array[i]); // print array by index
    }

    public static double[] square(double[] a) {
        double[] squared = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            squared[i] = a[i] * a[i];
        }
        return squared;
    }
}

OUTPUT:

1.0
4.0
4.0
16.0

For case 2:

import java.util.Arrays;

public class Practise {

    public static void main(String[] args) {
        double[] array = {1.0, 2.0, 2.0, 4.0};
        System.out.println(Arrays.toString(square(array)));
    }

    public static double[] square(double[] a) {
        double[] squared = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            squared[i] = a[i] * a[i];
        }
        return squared;
    }
}

OUTPUT:

[1.0, 4.0, 4.0, 16.0]

In the case 1 you can control and handle the output of the new array

score 0 · Answer 3 · answered May 29 '17 at 15:37

Instead of

  System.out.println(square(array));

use :

System.out.println(Arrays.toString(square(array)));

and see What's the simplest way to print a Java array?

NB : D@1540e19d is not a error.It's the hashCode() in hexadecimal. See http://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#toString--

Blasanka · Answer 4 · 2017-05-29T15:47:18.977

There is no error in your program. You are printing the memory address of array, which is [D@1db something like this. it is vary(because it is memory address).

Change:

System.out.println(square(array));

To:

 System.out.println(square(array)[0]);

tihs will only print index 0 value. If you want to print all the values in array you can do like this:

for(Double d: square(array)){
    System.out.println(d);
}

Here I have used for-each(enhanced for loop). If you are not familiar with this go with for loop.

score 0 · Answer 5 · answered May 29 '17 at 16:04

If I were you, I would create another array that stores the squared values ofdouble[] array = {1.0, 2.0, 3.0, 4.0}; . I don't think you need double[] squaredinside the method. Just use the one that you have given in the parameterlist.

public class square {
public static void main (String[] args){
    double[] array = {1.0, 2.0, 3.0, 4.0};
    double[] array1 = squareArray(array);
    for(double elem: array1){
        System.out.println(elem);
    }
}
public static double[] squareArray(double[] a){
    for(int i = 0; i < a.length; i++){
        a[i] *= a[i];
    }
    return a;
}
}

Array1 stores the squared values of array. I'm not quite sure what you're question is, but if it's about just printing out the array, the for-each-loop is a must-know for a beginner programmer. I've written it in the code. I'd strongly advice you to start using it and undertand its functionality. Hope this was helpful.

How to store and return the array with the squared result from array in method parameters

5 Answers5