How to print a returned array

Question

Surprisingly, I can't seem to find an answer to this anywhere.

I have initialized a new int array named "array" and done some things to it in a method named "reverse" and it returns array.length, how do I print the returned array in the main method and not the originally initialized array?

Here is my code, the for loop is what I am having problems with

public static void main(String[] args) 
{
    int array[] = new int [7];
    array[0] = 5 ;
    array[1] = 10;
    array[2] = 11;
    array[3] = 19;
    array[4] = 13;
    array[5] = 14;
    array[6] = 16;
         for(int i = 0; i < array.length; i++)
        {
            System.out.println(array[i]); 
        } 
    }
public int reverse(int[] array) {
    int left = 0;
    int right = array.length - 1;
    while( left < right ) 
    {  
        int temp = array[left];
        array[left] = array[right];
        array[right] = temp;
        left++;
    }
    return array.length;}

Please give us a short program that illustrates your problem. — Keppil, Mar 26 '14 at 21:17
You state, `"Here is my code, the for loop is what I am having problems with..."` -- which loop, and what problems are you having with it? Also, where do you call the method? You should consider making the method static so it can be called in the static main method without an instance. — Hovercraft Full Of Eels, Mar 26 '14 at 21:31

Epiglottal Axolotl · Answer 1 · 2014-03-26T21:25:10.420

1

You don't need to return anything. The way Java handles arrays, when you use the method it changes the contents of the original array. Thus, you can just print it as is.

edited Mar 26 '14 at 21:25

answered Mar 26 '14 at 21:19

Epiglottal Axolotl

1,048
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Use proper terminology. Arrays are not passed by reference. – Sotirios Delimanolis Mar 26 '14 at 21:20
1

@SotiriosDelimanolis I don't know any better terms to use for this. How would you say they are passed? – Epiglottal Axolotl Mar 26 '14 at 21:21
@Stendika Read [here](http://stackoverflow.com/questions/40480/is-java-pass-by-reference/40523#40523) for info on that. – Blue Ice Mar 26 '14 at 21:23
1

Array types are reference types. Reference type values are passed by value. What you should say is that an array object has a number of variables that are referenced by array access expressions. – Sotirios Delimanolis Mar 26 '14 at 21:23
OK, I guess I see your point. Updating my answer. (Although, the end result is exactly the same as if they were passed by reference, as far as I can tell.) – Epiglottal Axolotl Mar 26 '14 at 21:24
1

That's the point. It's not at all the same. Read Blue Ice's linked question/answers. Dereferencing and changing references are two completely different concepts. – Sotirios Delimanolis Mar 26 '14 at 21:26
So that reassigning variables in a method doesn't change anything. Good point. – Epiglottal Axolotl Mar 26 '14 at 21:28

score 0 · Accepted Answer · answered Mar 26 '14 at 21:32

For your specific code you need to:

Make your reverse method static, so it can be called from within the static main method without requiring that you first make an instance.

In other words, change the method signature to:

public static int reverse(int[] array) {

Then you need to call the method before iterating through the loop and printing out the results.

e.g.,

public static void main(String[] args) {
    int array[] = new int [7];
    array[0] = 5 ;
    array[1] = 10;
    array[2] = 11;
    array[3] = 19;
    array[4] = 13;
    array[5] = 14;
    array[6] = 16;
    reverse(array); // *** add this
    for(int i = 0; i < array.length; i++) {
        System.out.println(array[i]); 
    } 
}

How to print a returned array

2 Answers2