我了解其背后的逻辑,但不知道如何将其转换为代码。有人可以告诉我我写的这个例子吗?
小程序所做的只是中心矩形自行上下左右移动。我想用双缓冲区摆脱烦人的闪烁,但我不知道要进行什么更改/添加才能实现。
import java.applet.*;
import java.awt.*;
public class Broadway extends Applet implements Runnable {
Thread animation;
int locx,locy; // location of rectangle
int width, height; // dimensions of rectangle
// direction of motion
static final byte UP = 0;
static final byte DOWN = 1;
static final byte LEFT = 2;
static final byte RIGHT = 3;
byte state; // state the rect is in
// length of pausing interval in ms
static final int REFRESH_RATE = 100;
public void init() {
setBackground(Color.black);
locx = 80; // parameters of center rect
locy = 100;
width = 110;
height = 90;
state = UP;
}
public void start() {
animation = new Thread(this);
if (animation != null) {
animation.start();
}
}
public void paint(Graphics g) {
g.setColor(Color.yellow);
g.fillRect(0,0,90,90);
g.fillRect(250,0,40,190);
g.fillRect(80,110,100,20);
g.setColor(Color.blue);
g.fillRect(80,200,220,90);
g.fillRect(100,10,90,80);
g.setColor(Color.lightGray);
g.fillRect(locx,locy,width,height);
g.setColor(Color.red);
g.fillRect(200,0,45,45);
g.fillRect(0,100,70,200);
g.setColor(Color.magenta);
g.fillRect(200,55,60,135);
}
//update the center rectangle
void updateRectangle() {
switch (state) {
case DOWN:
locy += 2;
if (locy >= 110) {
state = UP;
}
break;
case UP:
locy -= 2;
if (locy <= 90) {
state = RIGHT;
}
break;
case RIGHT:
locx += 2;
if (locx >= 90) {
state = LEFT;
}
break;
case LEFT:
locx -= 2;
if (locx <= 70) {
state = DOWN;
}
break;
}
}
public void run() {
while (true) {
repaint();
updateRectangle();
try {
Thread.sleep (REFRESH_RATE);
} catch (Exception exc) { };
}
}
public void stop() {
if (animation != null) {
animation.stop();
animation = null;
}
}
}