How to return Array List element from method

Question

I'm trying to pass an individual elements of CordsArray from the public class Enemy() to the main.

public class Enemy {

//constructor
public Enemy()
{
    //*create array of coordinates
    ArrayList<Integer> CordArray = new ArrayList<Integer>();

    CordArray.add(0,2);
    CordArray.add(1,5);
    CordArray.add(2,8);
    CordArray.add(3,10);
}

public static int returnCords(int[] CordArray, int index) 
{   
    return CordArray[index]; 
}

I'm wanting to output elements of the CordArray to the console by calling returnCords in main:

System.out.println(returnCords(CordArray, 0));

But a 'CordArray cannot be resolved to a variable' error appears. Apologies for bad English.

Look at how you defined your variable CordArray in Enemy and look at the arg list for returnCords. You cannot pass an ArrayList when it is expecting an int array. — scrappedcola
– scrappedcola, Commented May 9, 2015 at 23:35
ChordArray is a local variable in your constructor and nothing else referenced it so it ceased to exist as soon as the constructor exited. — Alex Fitzpatrick
– Alex Fitzpatrick, Commented May 9, 2015 at 23:35

Suspended · Accepted Answer · 2015-05-09 23:41:40Z

1

The problems are:
-variable names should begin with lowercase letter,
-lists can contain single objects/values, you are trying to store two at one index

Create Coords object instead:

public class Coords{
    private int x;
    private int y;

    public Coords(int x, int y){
        this.x = x;
        this.y = y;
    }

    public int getX(){
        return x;
    }

    public int getY(){
        return y;
    }
}

Now you can do this:

ArrayList<Coords> cordArray = new ArrayList<Coords>();

Hope it helps.

answered May 9, 2015 at 23:41

Suspended

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2 Comments

Jyr Over a year ago

There are more problems with his code than the two you listed

Suspended Over a year ago

yes, visibility of CordsArray, the others are consequence of the two I mentioned.

DoubleMa · Accepted Answer · 2015-05-09 23:44:56Z

1

try using point and a global arraylist with a get function

import java.awt.Point;
import java.util.ArrayList;

public class Enemy {

    private final ArrayList<Point> points;

    public Enemy() {
        points = new ArrayList<>();
        points.add(new Point(2, 5));
        points.add(new Point(8, 10));
    }

    public ArrayList<Point> getPoints() {
        return points;
    }

    public static void main(String[] args) {
        Enemy enemy = new Enemy();
        int index = 0;
        Point point = enemy.getPoints().get(index);
        int x = point.x;
        int y = point.y;
    }
}

answered May 9, 2015 at 23:44

DoubleMa

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