Question

Sorry if the title didn’t make much sense. I’m making a Chip’s Challenge style game in Java Eclipse where special things like the Player, coins, and pushable blocks are a class. Interactions between the pushable block and the player require a lot of collision detection logic, and the code is getting atrocious because I have to do the same logic checks for each instance of the class. For example:

public void pb1TouchingBaddy() {

    if (pb1.getTileX() == b1.getTileX() & pb1.getTileY() == b1.getTileY()) {
        if (b1.getbUp() == 1 & pb1.getTileY() - 1 != pb2.getTileY()) {
            pb1.move(0, -1);
        } else if (b1.getbDown() == 1
                & pb1.getTileY() + 1 != pb2.getTileY()) {
            pb1.move(0, 1);
        } else if (b1.getbRight() == 1
                & pb1.getTileX() + 1 != pb2.getTileX()) {
            pb1.move(1, 0);
        } else if (b1.getbLeft() == 1
                & pb1.getTileX() - 1 != pb2.getTileX()) {
            pb1.move(-1, 0);
        }
    }

    if (pb1.getTileX() == b2.getTileX() & pb1.getTileY() == b2.getTileY()) {
        if (b2.getbUp() == 1 & pb1.getTileY() - 1 != pb2.getTileY()) {
            pb1.move(0, -1);
        } else if (b2.getbDown() == 1
                & pb1.getTileY() + 1 != pb2.getTileY()) {
            pb1.move(0, 1);
        } else if (b2.getbRight() == 1
                & pb1.getTileX() + 1 != pb2.getTileX()) {
            pb1.move(1, 0);
        } else if (b2.getbLeft() == 1
                & pb1.getTileX() - 1 != pb2.getTileX()) {
            pb1.move(-1, 0);
        }
    }

    if (pb1.getTileX() == b3.getTileX() & pb1.getTileY() == b3.getTileY()) {
        if (b3.getbUp() == 1 & pb1.getTileY() - 1 != pb2.getTileY()) {
            pb1.move(0, -1);
        } else if (b3.getbDown() == 1
                & pb1.getTileY() + 1 != pb2.getTileY()) {
            pb1.move(0, 1);
        } else if (b3.getbRight() == 1
                & pb1.getTileX() + 1 != pb2.getTileX()) {
            pb1.move(1, 0);
        } else if (b3.getbLeft() == 1
                & pb1.getTileX() - 1 != pb2.getTileX()) {
            pb1.move(-1, 0);
        }
    }

    if (pb1.getTileX() == b4.getTileX() & pb1.getTileY() == b4.getTileY()) {
        if (b4.getbUp() == 1 & pb1.getTileY() - 1 != pb2.getTileY()) {
            pb1.move(0, -1);
        } else if (b4.getbDown() == 1
                & pb1.getTileY() + 1 != pb2.getTileY()) {
            pb1.move(0, 1);
        } else if (b4.getbRight() == 1
                & pb1.getTileX() + 1 != pb2.getTileX()) {
            pb1.move(1, 0);
        } else if (b4.getbLeft() == 1
                & pb1.getTileX() - 1 != pb2.getTileX()) {
            pb1.move(-1, 0);
        }
    }

So as you can see those three blocks of if statements are all the exact same logic, just applied to different instances of the same object. Is there any way to write this without having to repeat myself so much? I was able to turn the four directional movement logic into one method and thought I was a genius for a while, but I can’t figure out how to do a similar thing but with multiple instances of the same object. Right now I’m stuck with just two of the pushable blocks before I get too confused and can’t do the logic for another one. Would appreciate any advice, thanks!

Answer 1

private function move(PBClass pb1, PBClass pb2, BClass b) {
    if (pb1.getTileX() == b.getTileX() & pb1.getTileY() == b.getTileY()) {
        if (b.getbUp() == 1 & pb1.getTileY() - 1 != pb2.getTileY()) {
            pb1.move(0, -1);
        } else if (b.getbDown() == 1
                & pb1.getTileY() + 1 != pb2.getTileY()) {
            pb1.move(0, 1);
        } else if (b.getbRight() == 1
                & pb1.getTileX() + 1 != pb2.getTileX()) {
            pb1.move(1, 0);
        } else if (b.getbLeft() == 1
                & pb1.getTileX() - 1 != pb2.getTileX()) {
            pb1.move(-1, 0);
        }
    }
}

public void pb1TouchingBaddy() {
    move(pb1, pb2, b1);
    move(pb1, pb2, b2);
    move(pb1, pb2, b3);
    move(pb1, pb2, b4);
}

of course you’ll need to replace PBClass and BClass with your actual class names.

If you have an array of objects:

PBClass[] listPB = { pb1, pb2, pb3, pb4};
BClass[] listB = { b1, b2, b3, b4};

public void pb1TouchingBaddy() {
    for (int i=0; i < listPB.length - 1; i+=2) {
        for (int j=0; j < listB.length; j++) {
            move(pb[i], pb[i+1], b[j]);
        }
    }
}

Or you can use ArrayLists in the same way