Java代码优化

Question

我刚刚做了一个教程，关于如何让一个角色在2d背景上移动，基本上就像一个非常有限的平台，没有重力或任何东西，我遇到了一些滞后，我假设这是因为按键/释放的工作方式，但我想知道是否有任何方法来优化它，它可能是我没有动画它只是简单的块，但我不确定，它就像如果我举着和左，然后我松开左，然后我按下右，而所有的时间仍然保持它只是向上，直到我松开，它滞后之间的左和右等。我将粘贴下面的代码。谢谢！：

//@@@MAIN CLASS, NAMED CHECKERS ARBITRARILY

import javax.swing.*;

public class Checkers {

public static void main(String[] args) {
    JFrame frame = new JFrame("2D Game");

    frame.add(new Board());

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(1200,326);
    frame.setVisible(true);
}
}


//@@@@@@@@@@@@@@@@@
//class called Dude this is my character(circle)

import javax.swing.ImageIcon;
import java.awt.Image;
import java.awt.event.KeyEvent;


public class Dude {
int x, dx, y, dy;
Image still;

public Dude(){
    ImageIcon i = new ImageIcon("C:/still.png");
    still = i.getImage();
    x = 10;
    y = 150;
}

public void move(){
    x = x + dx;
    y = y + dy;

}

public int getX(){
    return x;
}

public int getY(){
    return y;
}

public Image getImage(){
    return still;
}

public void keyPressed(KeyEvent e){
    int key = e.getKeyCode();

    if (key == KeyEvent.VK_LEFT)
        dx = -2;

   if (key == KeyEvent.VK_RIGHT)
        dx = 2;

   if (key == KeyEvent.VK_UP)
       dy = -2;

   if (key == KeyEvent.VK_DOWN)
       dy = 2;

}

    public void keyReleased(KeyEvent e){
    int key = e.getKeyCode();

    if (key == KeyEvent.VK_LEFT);
        dx = 0;

    if (key == KeyEvent.VK_RIGHT);
        dx = 0;

    if (key == KeyEvent.VK_UP)
       dy = 0;

    if (key == KeyEvent.VK_DOWN)
       dy = 0;

}

}


//@@@@@@@@@@@@@@@@@@@
//this is my board class (background)



import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.*;

public class Board extends JPanel implements ActionListener{

Dude p;
Image img;
Timer time;

public Board(){
    p = new Dude();
    addKeyListener(new AL());
    setFocusable(true);
    ImageIcon i = new ImageIcon("C:/test.png");
    img = i.getImage();
    time = new Timer(5, this);
    time.start();
}
public void actionPerformed(ActionEvent e){
    p.move();
    repaint();
}

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

            g2d.drawImage(img, 0, 0, null);
            g2d.drawImage(p.getImage(), p.getX(), p.getY(), null);
}

private class AL extends KeyAdapter{
    public void keyReleased(KeyEvent e){
        p.keyReleased(e);
    }
    public void keyPressed (KeyEvent e){
        p.keyPressed(e);
    }
}

}

Answer 1

这对我来说很有效：

package sof_6406645;

import javax.swing.*;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

public class Checkers {

    public static void main(String[] args) {
        JFrame frame = new JFrame("2D Game");

        frame.add(new Board());

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(1200,326);
        frame.setVisible(true);
    }
    public static class Board extends JPanel implements ActionListener {

        final Image img;
        Point p;
        final boolean[] dynamics = new boolean[4];

        public Board() {
            addKeyListener(new AL());
            setFocusable(true);
            ImageIcon i = new ImageIcon("dude.png");
            img = i.getImage();
            p = new Point(0,0);
            Timer timer = new Timer(5, this);
            timer.start();
        }
        public void actionPerformed(ActionEvent e){
            moveImage();
        }
        public void moveImage (){
            int dx = 0;
            int dy = 0;
            if(dynamics[0]) dx = -2; 
            if(dynamics[1]) dy = -2; 
            if(dynamics[2]) dx = 2; 
            if(dynamics[3]) dy = 2; 
            p.move((int)p.getX() + dx, (int)p.getY() + dy);
            repaint();
        }

        public void paint(Graphics g){
            super.paint(g);
            Graphics2D g2d = (Graphics2D) g;
            g2d.drawImage(img, (int)p.getX(), (int)p.getY(), null);
        }

        private class AL extends KeyAdapter{
            public void keyReleased(KeyEvent e){
                updateDynamics(e, false);
            }
            public void keyPressed (KeyEvent e){
                updateDynamics(e, true);
            }
        }
        final void updateDynamics(KeyEvent e, boolean v) {
            int i = e.getKeyCode() - KeyEvent.VK_LEFT;
            dynamics[i] = v;
        }
    }
}

编辑

做了一个小的修改以更正updateDynamics()上的签名，并抑制了手动内联(有效地)1行代码的冲动，这些代码将在两个关键的侦听器方法中重复。该方法调用应该由JIT内联。moveImage()中的if语句序列也可以简化为一半的检查，但我非常确定JVM会为您解决这一问题。

说到if，我最初并没有改变你的交互模式，但我认为如果你一直按两个相反的移动键，Dude应该会停止，你不这样认为吗？

        public void moveImage (){
            int dx = 0;
            int dy = 0;
            if(dynamics[0]) dx -= 2; 
            if(dynamics[1]) dy -= 2; 
            if(dynamics[2]) dx += 2; 
            if(dynamics[3]) dy += 2; 
            p.move((int)p.getX() + dx, (int)p.getY() + dy);
            repaint();
        }