Two ArrayList in run() method Collision Detection

Question

i have problem with checking collision with 2 arraylist that updating in run() method. here is my code in run() method:

 ArrayList enemy = addenemy.getEnemy();
        for (int i = 0; i < enemy.size(); i++) {
            Enemy p = (Enemy) enemy.get(i);
            if (p.isVisible() == true) {
                p.update();                    
            } else {
                enemy.remove(i);

            }}

ArrayList bullets = CharS.getBullets();
        for (int i = 0; i < bullets.size(); i++) {
            Bullets p = (Bullets) bullets.get(i);
            if (p.isVisible() == true) {
                p.update();
            } else {
                bullets.remove(i);

            }}

and here is my collision code in bullet class.

private void checkCollision() {
    ArrayList enemy = Game.getEnemy();
        for (int i = 0; i < enemy.size(); i++) {
            Enemy e = (Enemy) enemy.get(i);

        if(r.intersects(e.r)){
        visible = false;

        System.out.println("SHOTED");

        }}}

i got error when when enemy object removed(out of screen). how can i resolve this? thanks

i got this messages : Exception in thread "Thread-3" java.lang.NullPointerException — Nizarhdt, Oct 09 '13 at 22:29
The exception stack trace should show what line of code caused the NPE. Please identify what line of code in your posted code caused the exception. Also, what is `r` in the `checkCollision` method? — Ted Hopp, Oct 09 '13 at 22:32
this line `if(r.intersects(e.r)){` caused the exception. r is rectangle of bullets. its running normaly before enemy pass away from screen `enemy.remove(i);`. @Ted-Hopp — Nizarhdt, Oct 09 '13 at 22:39
If that line is throwing a NPE, then either `r` or `e` is `null` when that line executes. (Or perhaps `e.r`, if the NPE is being thrown from within the call to `intersects`.) — Ted Hopp, Oct 09 '13 at 23:51

score 0 · Accepted Answer · answered Oct 09 '13 at 22:45

0

Are you definining r as anything? I don't see anywhere where r is defined. This would cause your NullPointerException error.

Check the stack trace for the line number that the error is occurring on.

answered Oct 09 '13 at 22:45

RevMuun

58
1
5

thank you guys, its caused `r=null;` in my code. now my app running normally after delete it. thanks. – Nizarhdt Oct 09 '13 at 23:05

Two ArrayList in run() method Collision Detection

1 Answers1