如何使用 KeyListener 向左、向右、向上和向下移动对象似乎不起作用

Question

尝试使用向左、向右、向上和向下箭头让我的播放器移动，有一个名为 InputHandler 的类，它实现了 KeyListener 并在 KeyPressed 中有代码，例如 VK_LEFT 等，尝试使用 Switch 和 If Else 语句，也许我有点愚蠢

 Method to handle key presses captured by the GameGUI. The method calls
     * the game engine doTurn method to process a game turn for ANY key press,
     * but if the up, down, left or right arrow keys are pressed it also calls a
     * method in the engine to update the game by moving the player.
     *
     * @param e A KeyEvent object generated when a keyboard key is pressed

**
     * Handles the movement of the player when attempting to move in the game.
     * This method is automatically called by the InputHandler class when the
     * user has presses one of the arrow keys on the keyboard. The method should
     * check which direction for movement is required, by checking which
     * character was passed to this method (see parameter description below). If
     * the tile above, below, to the left or to the right is clear then the
     * player object should have its position changed to update its position in
     * the game window. If the target tile is not empty then the player should
     * not be moved, but other effects may happen such as giving a customer
     * food, or picking up food etc. To achieve this, the target tile should be
     * checked to determine the type of tile (food, table, wall etc.) and
     * appropriate methods called or attribute values changed.

@param direction A char representing the direction that the player should
     * move. U is up, D is down, L is left and R is right.

这些是我被告知要在代码中实现的内容，但箭头键似乎不会让玩家移动

public void keyPressed(KeyEvent e) {
        switch(e.getKeyCode()) {
            case KeyEvent.VK_LEFT:
                engine.movePlayer('L');
                break;  //handle left arrow key
            case KeyEvent.VK_RIGHT:
                engine.movePlayer('R');
                break;//handle right arrow
            case KeyEvent.VK_UP:
                engine.movePlayer('U');
                break;      //handle up arrow
            case KeyEvent.VK_DOWN:
                engine.movePlayer('D');
                break;  //handle down arrow
        }
        engine.doTurn();

上面的这段代码是我被告知要编辑的代码，这样当按下左箭头时玩家就会向左移动，上面的代码在 InputHandler 类中

public void movePlayer(char direction) {
switch (direction) {
            case 'U':
                // update player position and game state to move player up
                break;
            case 'L':
                // update player position and game state to move player left
                break;
            case 'R':
                // update player position and game state to move player right
                break;
            case 'D':
                // update player position and game state to move player down
                break;
            default:
                // code to execute if direction is none of the above
                break;
        }

上面的代码是我添加的代码，上面的代码在GameEngine类中

现在，每当我尝试运行这个项目时，都没有编译器错误，但箭头键似乎不会移动播放器

Answer 1

您需要显示GameEngine类的代码。 如果它包含玩家在屏幕上的x和y位置，则需要相应地更新它。

例如，如果你有玩家的x和y坐标（你应该考虑到你需要移动玩家），你可以执行以下操作：

public void movePlayer(char direction) {
        switch (direction) {
            case 'U':
                // update player position and game state to move player up
                y -= 1;
                break;
            case 'L':
                // update player position and game state to move player left
                x -= 1;
                break;
            case 'R':
                // update player position and game state to move player right
                x += 1;
                break;
            case 'D':
                // update player position and game state to move player down
                y += 1;
                break;
            default:
                // code to execute if direction is none of the above
                break;
        }

这是一个非常基本的实现，没有考虑速度和摩擦，并假设坐标系的(0,0)从屏幕的左上角开始。