尝试实现保持键绑定[关闭]

Question

我正在尝试构建一个类似于 Jetpack Joyride 的游戏，在该游戏中，用户可以按住空格向上，放手向下。我有一个重力测试版本运行良好，但我仍在试图弄清楚如何测试以查看是否按住空格键。我的想法是，按住空格键的时候可以设置spaceHeld为true，不按下的时候设置为false。这是我的代码：

import java.awt.event.*;
import javax.swing.*;
import java.util.Timer;
import java.util.TimerTask;
import java.util.Calendar;



public class Game {
    JFrame frame;
    JLabel player;

    boolean grounded = false;
    int velocity = 0;
    int finalY = 0;
    boolean spaceHeld = false;


    Action spaceAction;

    Game() {
         
        frame = new JFrame("Nicholas Seow-Xi Crouse");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(1920, 1080);
        frame.setLayout(null);

        player = new JLabel();
        player.setBackground(Color.red);
        player.setBounds(10, 1800, 50, 50);
        player.setOpaque(true);

        spaceAction = new SpaceAction();

        player.getInputMap().put(KeyStroke.getKeyStroke("SPACE"), "spaceAction");
        player.getActionMap().put("spaceAction", spaceAction);

        frame.add(player);
        frame.setVisible(true);
        
         Timer flightTime = new Timer();
         TimerTask flight = new TimerTask() {
         
            public void run() {
                  if(velocity > -5) {
                  velocity -= 1;
                  }
                  else{
                  velocity = -5;
                  }
                  if (finalY < -61) {
                   finalY = finalY + velocity;
                   }
                   else{
                   finalY = -61;
                   }
                   player.setLocation(player.getX(), player.getY() + finalY);
                   if (player.getY() <= 0){
                   cancel();
                   velocity = 0;
                   finalY = 0;
                   player.setLocation(player.getX(), 0);
                    
                   }  
            }
      };
         

         Timer gravityTime = new Timer();
         TimerTask gravity = new TimerTask() {


            //creates a timer run method that simulates the falling gravity when not grounded
            public void run() {
                if(velocity < 5){
                velocity += 1;
                }
                else{
                velocity = 5;
                }
                //creates the variable the tells where the player is located
                if (finalY < 61) {
                finalY = finalY + velocity;
                }
                else{
                finalY = 61;
                }
                player.setLocation(player.getX(), player.getY() + finalY);
                if (player.getY() >= 1000){
                cancel();
                velocity = 0;
                finalY = 0;
                player.setLocation(player.getX(), 990); 
                }
                
            }
        };

        if (grounded == false && spaceHeld == false ) {
            gravityTime.scheduleAtFixedRate(gravity, 0, 33);
        }
        if (grounded == false && spaceHeld == true ) {
            flightTime.scheduleAtFixedRate(flight, 0 ,33);
    }
}

   //Creates the SpaceAction method that recieves input from the keyboard and moves the player downward
    public class SpaceAction extends AbstractAction {
        public void actionPerformed(ActionEvent e) {
            spaceHeld = true;
            //creates the grounded variable the tells the computer whether or not the player is on the ground
            
            }

} 
} ```

the spaceHeld boolean is used to see if space is held to change values, while the grounded boolean tells the program that the user is on the ground. Help is appreciated!

Answer 1

如果您想知道space 键何时被按住，您应该使用两个事件。

1. 在keyPressed 上将您持有的boolean 设置为true
2. 在keyReleased 上将您持有的boolean 设置为false

这是一个小例子：

AtomicBoolean spaceHeld = new AtomicBoolean(false);

KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(ke ->
{
    switch (ke.getID())
    {
        case KeyEvent.KEY_PRESSED:
            if (ke.getKeyCode() == KeyEvent.VK_SPACE)
            {
                spaceHeld.set(true);
            }
            break;

        case KeyEvent.KEY_RELEASED:
            if (ke.getKeyCode() == KeyEvent.VK_SPACE)
            {
                spaceHeld.set(false);
            }
            break;
    }
    return false;
});