import java.awt.*; 
import javax.swing.*; 
import java.awt.event.*; 
class Counter extends WindowAdapter{ 
    static JFrame f=new JFrame("計(jì)算器"); 
    static JTextField text1=new JTextField("0."); 
    static String source=""; 
    static String cal=""; 
    static String object=""; 
    static boolean flag=false; 
    static boolean flag1=true; 
    static boolean flag2=false; 
    public void init(){ 
        try{ 
            Container c=f.getContentPane(); 
           //getContentPane()方法是是返回一個(gè)容器對象,可以通過這個(gè)對象
           //對容器進(jìn)行管理，如添加控件，和布局操作等；            
            JPanel pan1=new JPanel(); 
            JButton b1=new JButton("1"); 
            JButton b2=new JButton("2"); 
            JButton b3=new JButton("3"); 
            JButton b4=new JButton("4"); 
            JButton b5=new JButton("5"); 
            JButton b6=new JButton("6"); 
            JButton b7=new JButton("7"); 
            JButton b8=new JButton("8"); 
            JButton b9=new JButton("9"); 
            JButton b0=new JButton("0"); 
            JButton b11=new JButton("+"); 
            JButton b12=new JButton("-"); 
            JButton b13=new JButton("*"); 
            JButton b14=new JButton("/"); 
            JButton b15=new JButton("."); 
            JButton b16=new JButton("="); 
            JButton bclar=new JButton("C"); 
            text1.setHorizontalAlignment(JTextField.RIGHT); 
//setHorizontalAlignment方法的作用是讓標(biāo)簽中的文字內(nèi)容在標(biāo)簽內(nèi)按照指定的方式對齊。
            c.add(text1,"North"); 
            c.add(pan1); 
            A aa=new A(); 
            Result re=new Result(); 
            Opertion op=new Opertion(); 
            Clar cl=new Clar(); 
            b1.addActionListener(aa); 
            b2.addActionListener(aa); 
            b3.addActionListener(aa); 
            b4.addActionListener(aa); 
            b5.addActionListener(aa); 
            b6.addActionListener(aa); 
            b7.addActionListener(aa); 
            b8.addActionListener(aa); 
            b9.addActionListener(aa); 
            b0.addActionListener(aa); 
            b11.addActionListener(op); 
            b12.addActionListener(op); 
            b13.addActionListener(op); 
            b14.addActionListener(op); 
            b16.addActionListener(re); 
            b15.addActionListener(aa); 
            bclar.addActionListener(cl); 
            pan1.add(b1); 
            pan1.add(b2); 
            pan1.add(b3); 
            pan1.add(b11); 
            pan1.add(b4); 
            pan1.add(b5); 
            pan1.add(b6); 
            pan1.add(b12); 
            pan1.add(b7); 
            pan1.add(b8); 
            pan1.add(b9); 
            pan1.add(b13); 
            pan1.add(b0); 
            pan1.add(b15); 
            pan1.add(b16); 
            pan1.add(b14); 
            pan1.add(bclar); 
            f.setSize(200,220); 
            f.setVisible(true); 
        } 
        catch(Exception e){ 
            System.out.println(e.getMessage()); 
        } 
    } 
    class A implements ActionListener{ 
        public void actionPerformed(ActionEvent e){ 
            String a=text1.getText(); 
            String s=e.getActionCommand(); 
            if(a.equals("0.")||a.equals("+")||a.equals("-")||a.equals("*")||a.equals("/")) 
                text1.setText(s); 
            else{ 
                if(flag2){ 
                    text1.setText(s); 
                    flag2=false; 
                } 
                else 
                    text1.setText(a+s); 
            } 
        } 
    } 
    class Opertion implements ActionListener{ 
        public void actionPerformed(ActionEvent e){ 
            cal=e.getActionCommand(); 
            if(flag1==true) 
                 source=text1.getText(); 
            text1.setText(cal); 
            flag1=false; 
            flag=true; 
        } 
    } 
    class Result implements ActionListener{ 
        public void actionPerformed(ActionEvent e){ 
           double num1; 
           num1=Double.parseDouble(source); 
           object=text1.getText(); 
           double num2; 
           num2=Double.parseDouble(object); 
           double result=0; 
           if(cal.equals("+")) 
              result=num1+num2; 
           if(cal.equals("-")) 
              result=num1-num2; 
           if(cal.equals("*")) 
              result=num1*num2; 
           if(cal.equals("/")) 
              if(num2==0) 
                 text1.setText("除數(shù)不能為0"); 
              else 
                 result=num1/num2; 
           String s1=Double.toString(result); 
           text1.setText(s1); 
           flag1=true; 
           flag2=true; 
        } 
    } 
    class Clar implements ActionListener{ 
        public void actionPerformed(ActionEvent e){ 
           text1.setText("0."); 
        } 
    } 
    public static void main(String[] args){ 
        Counter count=new Counter(); 
        count.init(); 
    } 
    public void windowClosing(WindowEvent e){ 
        System.exit(1); 
    } 
    public void windowOpened(WindowEvent e){} 
    public void windowIconified(WindowEvent e){} 
    public void windowDeiconified(WindowEvent e){} 
    public void windowClosed(WindowEvent e){} 
    public void windowActivated(WindowEvent e){} 
    public void windowDeactivated(WindowEvent e){} 
}