大家都来看这个java程序好奇怪啊

答案:1 悬赏:80

解决时间 2021-04-28 13:38

提问者网友：喜遇你
2021-04-27 20:23

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Calendar;
import java.util.GregorianCalendar;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
class Clock extends JPanel implements ActionListener
{
private int hour;
private int minute;
private int second;
Clock()
{
  Timer timer=new Timer(1000,this);
  timer.start();
}
protected void paintComponent(Graphics g)
{
  super.paintComponent(g);
  setCurrentTime();
  int clockRadius=(int)(Math.min(getWidth(),getHeight()*0.4));
  int xCenter=getWidth()/2;
  int yCenter=getHeight()/2;
  //画时间刻度盘
  g.drawOval(xCenter-clockRadius,yCenter-clockRadius,2*clockRadius,2*clockRadius);
  g.drawString("12", xCenter-5 , yCenter-clockRadius+12);
  g.drawString("9", xCenter-clockRadius+3, yCenter+5);
  g.drawString("3",xCenter+clockRadius-10,yCenter+3);
  g.drawString("6",xCenter-3,yCenter+clockRadius-3);
  //画秒针
  int sLength=(int)(clockRadius*0.8);

  int xSecond=(int)(xCenter+sLength*1);
  int ySecond=(int)(yCenter-sLength*0);
// int xSecond=(int)(xCenter+sLength*Math.sin(15*6));
  //int ySecond=(int)(yCenter-sLength*Math.cos(15*6));

  g.setColor(Color.RED);
  g.drawLine(xCenter, yCenter, xSecond, ySecond);

}
public void actionPerformed(ActionEvent e)
{
  repaint();
}
public void setCurrentTime()
{
  Calendar cal=new GregorianCalendar();
  this.hour=cal.get(Calendar.HOUR_OF_DAY);
  this.minute=cal.get(Calendar.MINUTE);
  this.second=cal.get(Calendar.SECOND);
}
}
public class Example9_11 extends JFrame{
Example9_11()
{
  Clock clock=new Clock();
  this.add(clock);
}
public static void main(String[] args)
{
  Example9_11 f=new Example9_11();
  f.setTitle("时钟");
  f.setSize(300,250);
  f.setLocation(400,300);
  f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  f.setVisible(true);
}
}
运行结果是

但把

int xSecond=(int)(xCenter+sLength*1);
int ySecond=(int)(yCenter-sLength*0);
// int xSecond=(int)(xCenter+sLength*Math.sin(15*6));
//int ySecond=(int)(yCenter-sLength*Math.cos(15*6));

上面两句注销，下面两句的注销删掉

//int xSecond=(int)(xCenter+sLength*1);
// int ySecond=(int)(yCenter-sLength*0);
int xSecond=(int)(xCenter+sLength*Math.sin(15*6));
int ySecond=(int)(yCenter-sLength*Math.cos(15*6));

结果又是

Math.sin(15*6)不等于1吗

Math.cos(15*6)不等于0吗

最佳答案

二级知识专家网友：孤伤未赏
2021-04-27 20:58

Math.sin(15*6). 那个90 不是弧度，这个只可以是弧度。对180 Math.PI 乘或者除可以互相转换弧度和角度

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