Mega Code Archive
Create a thread to update Swing
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implements the Runnable interface.
extends the Thread class.
The threads must also create a run() method that accepts no
arguments and returns void. The run() method is called when the thread is started.
A thread is started by invoking the Thread.start() method. It can be stopped by
returning from the run() method.
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Clock extends JPanel implements Runnable {
Thread thread = null;
SimpleDateFormat formatter = new SimpleDateFormat("s", Locale.getDefault());
Date currentDate;
int xcenter = 100, ycenter = 100, lastxs = 0, lastys = 0, lastxm = 0, lastym = 0, lastxh = 0,
lastyh = 0;
private void drawStructure(Graphics g) {
g.setFont(new Font("TimesRoman", Font.PLAIN, 14));
g.setColor(Color.blue);
g.drawOval(xcenter - 50, ycenter - 50, 100, 100);
g.setColor(Color.darkGray);
g.drawString("9", xcenter - 45, ycenter + 3);
g.drawString("3", xcenter + 40, ycenter + 3);
g.drawString("12", xcenter - 5, ycenter - 37);
g.drawString("6", xcenter - 3, ycenter + 45);
}
public void paint(Graphics g) {
int xhour, yhour, xminute, yminute, xsecond, ysecond, second, minute, hour;
drawStructure(g);
currentDate = new Date();
formatter.applyPattern("s");
second = Integer.parseInt(formatter.format(currentDate));
formatter.applyPattern("m");
minute = Integer.parseInt(formatter.format(currentDate));
formatter.applyPattern("h");
hour = Integer.parseInt(formatter.format(currentDate));
xsecond = (int) (Math.cos(second * 3.14f / 30 - 3.14f / 2) * 45 + xcenter);
ysecond = (int) (Math.sin(second * 3.14f / 30 - 3.14f / 2) * 45 + ycenter);
xminute = (int) (Math.cos(minute * 3.14f / 30 - 3.14f / 2) * 40 + xcenter);
yminute = (int) (Math.sin(minute * 3.14f / 30 - 3.14f / 2) * 40 + ycenter);
xhour = (int) (Math.cos((hour * 30 + minute / 2) * 3.14f / 180 - 3.14f / 2) * 30 + xcenter);
yhour = (int) (Math.sin((hour * 30 + minute / 2) * 3.14f / 180 - 3.14f / 2) * 30 + ycenter);
// Erase if necessary, and redraw
g.setColor(Color.lightGray);
if (xsecond != lastxs || ysecond != lastys) {
g.drawLine(xcenter, ycenter, lastxs, lastys);
}
if (xminute != lastxm || yminute != lastym) {
g.drawLine(xcenter, ycenter - 1, lastxm, lastym);
g.drawLine(xcenter - 1, ycenter, lastxm, lastym);
}
if (xhour != lastxh || yhour != lastyh) {
g.drawLine(xcenter, ycenter - 1, lastxh, lastyh);
g.drawLine(xcenter - 1, ycenter, lastxh, lastyh);
}
g.setColor(Color.darkGray);
g.drawLine(xcenter, ycenter, xsecond, ysecond);
g.setColor(Color.red);
g.drawLine(xcenter, ycenter - 1, xminute, yminute);
g.drawLine(xcenter - 1, ycenter, xminute, yminute);
g.drawLine(xcenter, ycenter - 1, xhour, yhour);
g.drawLine(xcenter - 1, ycenter, xhour, yhour);
lastxs = xsecond;
lastys = ysecond;
lastxm = xminute;
lastym = yminute;
lastxh = xhour;
lastyh = yhour;
}
public void start() {
if (thread == null) {
thread = new Thread(this);
thread.start();
}
}
public void stop() {
thread = null;
}
public void run() {
while (thread != null) {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
}
repaint();
}
thread = null;
}
public void update(Graphics g) {
paint(g);
}
public static void main(String args[]) {
JFrame window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setBounds(30, 30, 300, 300);
Clock clock = new Clock();
window.getContentPane().add(clock);
window.setVisible(true);
clock.start();
}
}
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