📅  最后修改于: 2020-10-01 04:20:28             🧑  作者: Mango
可以通过使用Math类来创建模拟时钟。让我们看一个简单的例子:
import java.applet.*;
import java.awt.*;
import java.util.*;
import java.text.*;
public class MyClock extends Applet implements Runnable {
int width, height;
Thread t = null;
boolean threadSuspended;
int hours=0, minutes=0, seconds=0;
String timeString = "";
public void init() {
width = getSize().width;
height = getSize().height;
setBackground( Color.black );
}
public void start() {
if ( t == null ) {
t = new Thread( this );
t.setPriority( Thread.MIN_PRIORITY );
threadSuspended = false;
t.start();
}
else {
if ( threadSuspended ) {
threadSuspended = false;
synchronized( this ) {
notify();
}
}
}
}
public void stop() {
threadSuspended = true;
}
public void run() {
try {
while (true) {
Calendar cal = Calendar.getInstance();
hours = cal.get( Calendar.HOUR_OF_DAY );
if ( hours > 12 ) hours -= 12;
minutes = cal.get( Calendar.MINUTE );
seconds = cal.get( Calendar.SECOND );
SimpleDateFormat formatter
= new SimpleDateFormat( "hh:mm:ss", Locale.getDefault() );
Date date = cal.getTime();
timeString = formatter.format( date );
// Now the thread checks to see if it should suspend itself
if ( threadSuspended ) {
synchronized( this ) {
while ( threadSuspended ) {
wait();
}
}
}
repaint();
t.sleep( 1000 ); // interval specified in milliseconds
}
}
catch (Exception e) { }
}
void drawHand( double angle, int radius, Graphics g ) {
angle -= 0.5 * Math.PI;
int x = (int)( radius*Math.cos(angle) );
int y = (int)( radius*Math.sin(angle) );
g.drawLine( width/2, height/2, width/2 + x, height/2 + y );
}
void drawWedge( double angle, int radius, Graphics g ) {
angle -= 0.5 * Math.PI;
int x = (int)( radius*Math.cos(angle) );
int y = (int)( radius*Math.sin(angle) );
angle += 2*Math.PI/3;
int x2 = (int)( 5*Math.cos(angle) );
int y2 = (int)( 5*Math.sin(angle) );
angle += 2*Math.PI/3;
int x3 = (int)( 5*Math.cos(angle) );
int y3 = (int)( 5*Math.sin(angle) );
g.drawLine( width/2+x2, height/2+y2, width/2 + x, height/2 + y );
g.drawLine( width/2+x3, height/2+y3, width/2 + x, height/2 + y );
g.drawLine( width/2+x2, height/2+y2, width/2 + x3, height/2 + y3 );
}
public void paint( Graphics g ) {
g.setColor( Color.gray );
drawWedge( 2*Math.PI * hours / 12, width/5, g );
drawWedge( 2*Math.PI * minutes / 60, width/3, g );
drawHand( 2*Math.PI * seconds / 60, width/2, g );
g.setColor( Color.white );
g.drawString( timeString, 10, height-10 );
}
}