}//主方法

//點類

package Circle;public class Point {public double x,y;double getLance(Point p1,Point p2){double lance = Math.sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y));return lance;}void setXY(double i,double j){x=i;y=j;}public Point(double i,double j){x=i;y=j;}}

//圓類，繼承點類

package Circle;public class Circlearea extends Point {double r;public Circlearea(){super(0,0);//調用父類的構造方法}public double getarea(Point p1,Point p2){r=Math.sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y));double area=3.14*r*r;return area;}}

//窗體顯示類

package Circle;import java.awt.*;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import javax.swing.*;/*** @author admin* wirte win**/public class Getdata extends Frame{/*** */private static final long serialVersionUID = 6165187708490829110L;TextField text1=new TextField(5);TextField text2=new TextField(5);TextField text3=new TextField(5);TextField text4=new TextField(5);Button button1=new Button("確認計算");Button button2=new Button("清零");//public Getdata(){super("計算");setLocationRelativeTo(null);setLayout(new FlowLayout());add(new JLabel("第一個點xy坐標"));add(text1);add(text2);add(new JLabel("第二個點xy坐標"));add(text3);add(text4);add(button1);add(button2);//button2.setBackground(Color.lightGray);addWindowListener(new WindowCloser());pack();setVisible(true);button1.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){if(e.getSource() == button1){double a,b,c,d;a=Double.parseDouble(text1.getText());b=Double.parseDouble(text2.getText());c=Double.parseDouble(text3.getText());d=Double.parseDouble(text4.getText());System.out.println(a);Point p1=new Point(a,b);Point p2=new Point(c,d);System.out.println(p1.toString());Circlearea cir=new Circlearea();double f=cir.getarea(p1, p2);String str =Double.toString(f);showAnswer(str);}else{System.out.print("出錯");}}});button2.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){if(e.getSource() == button2){text1.setText("");text2.setText("");text3.setText("");text4.setText("");}else{System.out.print("出錯");}}});setWindowIcon();//}/** 圖標修改,shift alt j*/public void setWindowIcon() //{ ImageIcon imageIcon = new ImageIcon(getClass().getResource("/img/ico.png")); this.setIconImage(imageIcon.getImage()); } private class WindowCloser extends WindowAdapter{public void windowClosing(WindowEvent we){System.exit(0);}}public void showAnswer(String str){JOptionPane.showMessageDialog(null, "結果為："+str,"結果",JOptionPane.INFORMATION_MESSAGE);}}