我无法在Java中获得正确的算法

Question

I'm working on a small game where walls come at you and you have to dodge them by getting through gaps

My problem is that I can't get my gaps equal sized

int x = random.nextInt(Game.WD - 200) + 100;
int y;  
int HEIGHT = 10;
int WIDTH = Game.WD - x;
int gap = 100;

public void paint(Graphics g){
    g.drawRect(x, y, WIDTH , HEIGHT); //right part
    g.drawRect(-x, y, (Game.WD - gap)  , HEIGHT); //left part

I know it has something to do with this part of the class. when i run this, it gives me unequal gaps. i hope this is sufficient information.

game.WD is equal to 500

Here is the whole class just in case:

import java.awt.Graphics;

import java.awt.Rectangle; import java.util.Random;

public class Border

Random random = new Random();

int x = random.nextInt(Game.WD - 200) + 100;
int y; 
int speed = - 6;    
int HEIGHT = 10;
int WIDTH = Game.WD - x;
int gap = 100;


@SuppressWarnings("unused")
private Game game;

public Border(int i) {
    this.y = i;
}


public void paint(Graphics g){
    g.drawRect(x, y, WIDTH , HEIGHT);
    g.drawRect(-x, y, (Game.WD - gap)  , HEIGHT);

}

public Rectangle getBounds3(){
    return new Rectangle(x, y, WIDTH, HEIGHT);
}

public Rectangle getBounds4(){
    return new Rectangle(x, y, WIDTH, HEIGHT);
}

public void move() {
    y += speed;


    if (y <= 0){
        y = Game.HE;
        x = random.nextInt(Game.WD - 200) + 100;
        WIDTH = Game.WD - x;
    }

}

Answer 1

-x is your mistake, it makes no sense to use a value that is a mirror of x in the y axis.

For this:

0--a<gap>x---b

Define like so:

//a+gap = x so:
a = x - gap;
b = Game.WD - x;

g.drawRect(0, y, a, HEIGHT); //left part
g.drawRect(x, y, b, HEIGHT); //right part