# How do I place these numbers into an array

• 07-18-2009, 04:36 PM
mainy
How do I place these numbers into an array
Hello,

I am struggling with a fairly simple problem which I hope you can help with. I am working on a some code but there is a small part of it which I can't seem to get to work.

I have two classes. I want to enter details into one, which will place those details into an array which can then be accessed.

Class one:
Code:

```public class Triangle {         int x, y, l;         int[] cx;         int[] cy;         public Triangle(int x, int y, int l) {             this.x = x;             this.y = y;             this.l = l;         }         public void cords(){           cy[0] = x;           cx[1] = x+10;           cx[2] = x+20;           cy[0] = y;           cy[1] = y+20;           cy[2] = y;     }  }```
Then I have a class to test it:
Code:

```public class Test {     public static void main(String[] args) {         Triangle tos = new Triangle(100, 200, 3);         System.out.println(tos.cy[0]);         } }```
• 07-18-2009, 06:53 PM
hardwired
Before you can use an array you must instantiate it:
Code:

```int[] x;              // declaration int[] y = new int[4];  // declaration and instantiation```
Code:

```public class TriangleRx {     int x, y, l;     int[] cx;     int[] cy;     public TriangleRx(int x, int y, int l) {         this.x = x;         this.y = y;         this.l = l;         System.out.println("cx = " + cx + "  cy = " + cy);     }     public void cords() {         cy[0] = x;         cx[1] = x+10;         cx[2] = x+20;         cy[0] = y;         cy[1] = y+20;         cy[2] = y;     }     public static void main(String[] args) {         TriangleRx test = new TriangleRx(2, 3, 5); //        test.cords();     } }```
• 07-19-2009, 07:57 PM
Harpreet1111
u r using the array without instantiating it. just add

cx=new int[size of array];
cy=new int[]size of array];

in constructor and the job is done......