需要一种方法让我的角色在向左/向右移动时跳跃

Question

I have already got the jumping on the y-axis running fine, but I want to be able to use 'dx' from jumping while pressing the left/right key (ex. if I am pressing right key to go right and jump while still holding it, the character will move in a "diagonal" way)

My main jumping code (timer activated when jump key is pressed):

 public void actionPerformed (ActionEvent e) {
    dy += 1;
        y_pos += dy;
    if (y_pos >= 400) {
        dy = 0;
        y_pos = 400;
       timer.stop();
    }   
    repaint();
}  

Now my KeyEvent code:

            if (command == KeyEvent.VK_RIGHT){
                x_pos += 5;
                right = true;
            }
            if (command == KeyEvent.VK_LEFT) {
                x_pos -= 5;
                right = false;
            }
            if (command == KeyEvent.VK_UP) {    
                if (!(timer.isRunning()))
                    dy = -20;   
                timer.start();
            }   
            dr.repaint();

Answer 1

Below is how I would implement the input logic. Note that there are several choices when you want to dig further into input handling. Using this implementation, keyboard inputs are separated from the effects they have on the game world, which is handy in several ways. For example, the speed of the character is constant (given the timing of the game loop / movements is handled correctly) regardless of the frequency of key presses / repeats.

Anyway, some pseudo code:

// Global:
array keysdown;
keysdown[left] = false;
keysdown[right] = false;
keysdown[up] = false;

// The all-important game loop:
while (true) {
    pollInputs();
    doMovement();
    draw();
}

function pollInputs () {
    foreach (key that you want to handle) {
        if (key.state == down) {
            keysdown[key] = true;
        } else {
            keysdown[key] = false;
        }
    }
}

function doMovement () {
    if (keysdown[left]) {
        // move character left
    } else if (keysdown[right]) {
        // move character right
    }

    if (keysdown[up]) {
        // initiate jump
    }
}