按键与播放器 animation 发生之间的延迟（KeyListener，Java）

Question

I am new to stack overflow so please excuse me if i make any mistakes.

I am writing a java game with moving player which is animated, however when i press the keys to move said player (W, A, S and D), the player stops, waits a bit, then walks normally. It is like w.....wwwwwwwwwwwwwwwwwwww where the. means the player isnt moving.

I have looked up many solutions however none of them work for some reason. Even when i use setters to set the animation...the same thing happens.

Is my code wrong? Am i missing something??

Here is the class with the player and KeyListener. Is there something wrong?

import javax.swing.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.*;


class Play extends JPanel implements KeyListener, ActionListener{
JFrame playFrame = new JFrame("Play");

int xPos = 295;
int yPos= 215;

int xWorld = 0;
int yWorld = 0;

int worldSizeX = 640;
int worldSizeY = 480; 

boolean w, a, s, d, shift, esc, b;

Font font;

private BufferedImage[] walkingDown = {Sprite.getSprite(0,0), Sprite.getSprite(1,0), Sprite.getSprite(2,0), Sprite.getSprite(3,0)};
private BufferedImage[] walkingDownLeft = {Sprite.getSprite(0,1), Sprite.getSprite(1,1), Sprite.getSprite(2,1), Sprite.getSprite(3,1)};
private BufferedImage[] walkingDownRight = {Sprite.getSprite(0,2), Sprite.getSprite(1,2), Sprite.getSprite(2,2), Sprite.getSprite(3,2)};
private BufferedImage[] walkingUp = {Sprite.getSprite(0,5), Sprite.getSprite(1,5), Sprite.getSprite(2,5), Sprite.getSprite(3,5)};
private BufferedImage[] walkingUpLeft = {Sprite.getSprite(0,6), Sprite.getSprite(1,6), Sprite.getSprite(2,6), Sprite.getSprite(3,6)};
private BufferedImage[] walkingUpRight = {Sprite.getSprite(0,7), Sprite.getSprite(1,7), Sprite.getSprite(2,7), Sprite.getSprite(3,7)};
private BufferedImage[] walkingLeft = {Sprite.getSprite(0,3), Sprite.getSprite(1,3), Sprite.getSprite(2,3), Sprite.getSprite(3,3)};
private BufferedImage[] walkingRight = {Sprite.getSprite(0,4), Sprite.getSprite(1,4), Sprite.getSprite(2,4), Sprite.getSprite(3,4)};
private BufferedImage[] standing = {Sprite.getSprite(0,0)};

private Animation walkDown = new Animation(walkingDown, 12);
private Animation walkDownLeft = new Animation(walkingDownLeft, 12);
private Animation walkDownRight = new Animation(walkingDownRight, 12);
private Animation walkUp = new Animation(walkingUp, 12);
private Animation walkUpLeft = new Animation(walkingUpLeft, 12);
private Animation walkUpRight = new Animation(walkingUpRight, 12);
private Animation walkLeft = new Animation(walkingLeft, 12);
private Animation walkRight = new Animation(walkingRight, 12);
private Animation stand = new Animation(standing, 12);

private BufferedImage[] rollingDown = {Sprite.getSprite(0,8), Sprite.getSprite(1,8), Sprite.getSprite(2,8), Sprite.getSprite(3,8)};
private BufferedImage[] rollingDownLeft = {Sprite.getSprite(0,9), Sprite.getSprite(1,9), Sprite.getSprite(2,9), Sprite.getSprite(3,9)};
private BufferedImage[] rollingDownRight = {Sprite.getSprite(0,10), Sprite.getSprite(1,10), Sprite.getSprite(2,10), Sprite.getSprite(3,10)};
private BufferedImage[] rollingUp = {Sprite.getSprite(0,13), Sprite.getSprite(1,13), Sprite.getSprite(2,13), Sprite.getSprite(3,13)};
private BufferedImage[] rollingUpLeft = {Sprite.getSprite(0,14), Sprite.getSprite(1,14), Sprite.getSprite(2,14), Sprite.getSprite(3,14)};
private BufferedImage[] rollingUpRight = {Sprite.getSprite(0,15), Sprite.getSprite(1,15), Sprite.getSprite(2,15), Sprite.getSprite(3,15)};
private BufferedImage[] rollingLeft = {Sprite.getSprite(0,11), Sprite.getSprite(1,11), Sprite.getSprite(2,11), Sprite.getSprite(3,11)};
private BufferedImage[] rollingRight = {Sprite.getSprite(0,12), Sprite.getSprite(1,12), Sprite.getSprite(2,12), Sprite.getSprite(3,12)};

private Animation rollDown = new Animation(rollingDown, 12);
private Animation rollDownLeft = new Animation(rollingDownLeft, 12);
private Animation rollDownRight = new Animation(rollingDownRight, 12);
private Animation rollUp = new Animation(rollingUp, 12);
private Animation rollUpLeft = new Animation(rollingUpLeft, 12);
private Animation rollUpRight = new Animation(rollingUpRight, 12);
private Animation rollLeft = new Animation(rollingLeft, 12);
private Animation rollRight = new Animation(rollingRight, 12);

private Animation animation = stand;

Timer timer = new Timer(12, this);

public Play(){
    playFrame.setPreferredSize(new Dimension(640,480));
    playFrame.pack();
    playFrame.setResizable(false);
    playFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    playFrame.setLocationRelativeTo(null);

    addKeyListener(this);
    setFocusable(true);

    timer.start();

    playFrame.setVisible(true);
}

public void paintComponent(Graphics g){
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D)g;

    setBackground(Color.CYAN);

    g2d.setColor(Color.GREEN);
    g2d.fillRect(xWorld,yWorld, 640,480);

    g2d.drawImage(animation.getSprite(), xPos, yPos, null);

    if(esc == true){
        g2d.setColor(Color.BLACK);
        g2d.fillRect(0,0, 640,480);

        try{
            font = Font.createFont(Font.TRUETYPE_FONT, new File("pixelated/pixelated.ttf"));
            GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
            ge.registerFont(Font.createFont(Font.TRUETYPE_FONT, new File("pixelated/pixelated.ttf")));
        }catch(IOException|FontFormatException e){
        }

        g2d.setFont(font.deriveFont(80f));
        g2d.setColor(Color.WHITE);
        g2d.drawString("Paused", 205,80);

        g2d.setFont(font.deriveFont(30f));
        g2d.drawString("To resume, press W, A, S or D", 150,150);

        g2d.drawString("Or", 305,240);

        g2d.drawString("Press ESCAPE + B to go back to MainMenu <--", 40,320);

        if(esc == true && w == true){
            esc = false;
        }
        if(esc == true && a == true){
            esc = false;
        }
        if(esc == true && s == true){
            esc = false;
        }
        if(esc == true && d == true){
            esc = false;
        }
    }
}

public void keyPressed(KeyEvent e){
    if(e.getKeyCode() == KeyEvent.VK_W) w = true;
    if(e.getKeyCode() == KeyEvent.VK_A) a = true;
    if(e.getKeyCode() == KeyEvent.VK_S) s = true;
    if(e.getKeyCode() == KeyEvent.VK_D) d = true;
    if(e.getKeyCode() == KeyEvent.VK_SHIFT) shift = true;
    if(e.getKeyCode() == KeyEvent.VK_ESCAPE) esc = true;
    if(e.getKeyCode() == KeyEvent.VK_B) b = true;

    //walking
    if(w == true){      
        yWorld = yWorld+1;

        animation = walkUp;
        animation.start();

        repaint();
    }
    if(a == true){
        xWorld = xWorld+1;

        animation = walkLeft;
        animation.start();

        repaint();
    } 
    if(s == true){
        yWorld = yWorld-1;

        animation = walkDown;
        animation.start();

        repaint();
    }
    if(d == true){
        xWorld = xWorld-1;

        animation = walkRight;
        animation.start();

        repaint();
    }

    if(w==true && a==true){
        yWorld = yWorld+1;
        xWorld = xWorld+1;

        animation = walkUpLeft;
        animation.start();
    }       
    if(w==true && d==true){
        yWorld = yWorld+1;
        xWorld = xWorld-1;

        animation = walkUpRight;
        animation.start();
    }       
    if(s==true && a==true){
        yWorld = yWorld-1;
        xWorld = xWorld+1;

        animation = walkDownLeft;
        animation.start();
    }       
    if(s==true && d==true){
        yWorld = yWorld-1;
        xWorld = xWorld-1;

        animation = walkDownRight;
        animation.start();
    }

    //rolling
    if(w==true && shift==true){
        yWorld = yWorld+5;

        animation = rollUp;
        animation.start();

        repaint();
    }
    if(a==true && shift==true){
        xWorld = xWorld+5;

        animation = rollLeft;
        animation.start();

        repaint();
    }
    if(s==true && shift==true){
        yWorld = yWorld-5;

        animation = rollDown;
        animation.start();

        repaint();
    }
    if(d==true && shift==true){
        xWorld = xWorld-5;

        animation = rollRight;
        animation.start();

        repaint();
    }

    if(w==true && a==true &&shift==true){
        yWorld = yWorld+1;
        xWorld = xWorld+1;

        animation = rollUpLeft;
        animation.start();
    }       
    if(w==true && d==true &&shift==true){
        yWorld = yWorld+1;
        xWorld = xWorld-1;

        animation = rollUpRight;
        animation.start();
    }       
    if(s==true && a==true &&shift==true){
        yWorld = yWorld-1;
        xWorld = xWorld+1;

        animation = rollDownLeft;
        animation.start();
    }       
    if(s==true && d==true &&shift==true){
        yWorld = yWorld-1;
        xWorld = xWorld-1;

        animation = rollDownRight;
        animation.start();
    }

    if(esc == true && b == true){
        esc = false;

        playFrame.setVisible(false);

        new MainMenu();
    }
}

public void keyReleased(KeyEvent e){
    if(e.getKeyCode() == KeyEvent.VK_W) w = false;
    if(e.getKeyCode() == KeyEvent.VK_A) a = false;
    if(e.getKeyCode() == KeyEvent.VK_S) s = false;
    if(e.getKeyCode() == KeyEvent.VK_D) d = false;
    if(e.getKeyCode() == KeyEvent.VK_SHIFT) shift = false;
    if(e.getKeyCode() == KeyEvent.VK_B) b = false;

    if(w == false){
        animation.stop();
        animation.reset();
        animation = stand;
    }

    if(a == false){
        animation.stop();
        animation.reset();
        animation = stand;
    }

    if(s == false){
        animation.stop();
        animation.reset();
        animation = stand;
    }

    if(d == false){
        animation.stop();
        animation.reset();
        animation = stand;
    }

    if(shift == false){
        animation.stop();
        animation.reset();
        animation = stand;
    }
}

public void keyTyped(KeyEvent e){
}

public void actionPerformed(ActionEvent e){     
    animation.update();

    if(yPos < yWorld){
        yWorld = yPos;
        yPos = yWorld;
    }
    if(xPos < xWorld){
        xWorld = xPos;
        xPos = xWorld;
    }       
    if((yPos+64) > (yWorld+worldSizeY)){
        yWorld = yPos-worldSizeY+64;
        yPos = (yWorld+worldSizeY)-64;
    }
    if((xPos+64) > (xWorld+worldSizeX)){
        xWorld = xPos-worldSizeX+64;
        xPos = (xWorld+worldSizeX)-64;  
    }
  }
}

Answer 1

when i press the keys to move said player (W, A, S and D), the player stops, waits a bit, then walks normally.

This is because the "repeat rate" of the keyboard is controlled by a setting in your OS. Don't rely on the OS to generate events.

Instead you should be using a Swing Timer to schedule the events. When the key is:

1. pressed, you start the Timer.
2. released, you stop the Timer.

Also you should be using "Key Bindings", not a KeyListener.

Read the sections from the Swing tutorial on:

1. How to Use Swing Timers
2. How to Use Key Bindings

for more information on these concepts.

You can also check out: Motion Using the Keyboard . The Keyboard Animation example incorporates the above two suggestions. Also, a painting method is for painting only. You should NOT:

1. read the font file
2. set property values

You can't control when the paintComponent() method is called, so you should only paint the current state of your class. You need other methods to change the state of your variables.