Error Setting Object Array Values

Question

package net.gfx;

public class TileSet {

    public final int TILES = 627;

    class Tiles {
        int x = 0, y = 0;
        int w = 0, h = 0;

    }

    public Tiles tiles[] = new Tiles[TILES];

    public TileSet() {
        for (int i = 0, y = 0; i < TILES; i++) {
            for (int x = 0; x < 1280; x =+ 25) {
                if (x > 1280) {
                    x = 0;
                    y += 40;

                }
                else {
                    tiles[i].x = x; //ERROR CAUSED HERE
                    tiles[i].y = y; //TO HERE *Unknown reason*
                    tiles[i].w = 40;
                    tiles[i].h = 40;

                }

            }

        }

    }

}

The Error im getting:

Exception in thread "main" java.lang.ExceptionInInitializerError
    at net.jump.Jump.<clinit>(Jump.java:8)
Caused by: java.lang.NullPointerException
    at net.gfx.TileSet.<init>(TileSet.java:24)
    at net.gfx.Graphics.<clinit>(Graphics.java:10)
    ... 1 more

What I'm trying to do is basically create an array of tiles on a screen. Everyting else works besides the setting the Object array Values.

I've searched almost everywhere and haven't found anything. I bet its probaly some simple thing i missed.

Can you provide more Infos about the Framework you use for the Tiles? Simple approach without further knowledge: Why don't you set the values before you store the tiles in the set? — arnoapp
– arnoapp, Commented Sep 5, 2013 at 0:57

RandomQuestion · Accepted Answer · 2013-09-05 00:42:15Z

2

You have to create an instance of Tiles before you can do any operation on it.

 for (int i = 0, y = 0; i < TILES; i++) {
    for (int x = 0; x < 1280; x =+ 25) {
        if (x > 1280) {
            x = 0;
            y += 40;

        }
        else {
            tiles[i] = new Tiles(); //instance created here.
            tiles[i].x = x; 
            tiles[i].y = y; 
            tiles[i].w = 40;
            tiles[i].h = 40;

        }

    }

}

answered Sep 5, 2013 at 0:42

RandomQuestion

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Comments

Josh M · Accepted Answer · 2013-09-05 00:38:18Z

1

You aren't initializing each Tiles in your array, as the default value is null.

Perhaps you should try initializing each Tiles:

for(int i = 0; i < tiles.length; i++){
    tiles[i] = new Tiles();
}

After that, you could perform operations with each Tiles element in the array.

answered Sep 5, 2013 at 0:38

Josh M

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1 Comment

Greymouth Over a year ago

I've Implemented that code and every time I run it just freezes up.

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