/*****************************************
將UI20改成Applet與Application兩用版本
*************************************************/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//由JFrame改成 JApplet
public class ui40 extends JApplet implements ActionListener
{
    JButton bot[]=new JButton[10];
    JButton bot_dt=new JButton(".");
    JButton bot_a=new JButton("+");
    JButton bot_s=new JButton("-");
    JButton bot_m=new JButton("*");
    JButton bot_d=new JButton("/");
    JButton bot_e=new JButton("=");
    JButton bot_c=new JButton("C");
    JButton bot_off=new JButton("OFF");
    JTextField txt;
    Container c;
    JPanel jpl=new JPanel();
    JScrollPane jscp=new JScrollPane(jpl);
    String name;
    double A=0,B=0;
    int op=0,dot=0;
    public void init() //由建構元改成 public void init()
    {
        //super("UI 版面配置"); 不用super了
        int i;
        for (i=0;i<10;i=i+1)
        {
            bot[i]=new JButton(Integer.toString(i));
        }
        txt=new JTextField(10);
        txt.setEditable(false);//設定成不能修改
        txt.setHorizontalAlignment(JTextField.RIGHT);//靠右對齊
        c=getContentPane();
        c.setLayout(new BorderLayout());//設定為用Borderlayout
        jpl.setLayout(new GridLayout(5,4));//設定為用gridlayout
        c.add(txt,BorderLayout.NORTH);
        c.add(jscp,BorderLayout.CENTER);//用scrollpane
        //注意加入元件的順序
        for (i=0;i<10;i=i+1)
        {
            jpl.add(bot[i]);
            bot[i].addActionListener(this);
        }
        jpl.add(bot_dt);
        bot_dt.addActionListener(this);
        jpl.add(bot_a);
        bot_a.addActionListener(this);
        jpl.add(bot_s);
        bot_s.addActionListener(this);
        jpl.add(bot_m);
        bot_m.addActionListener(this);
        jpl.add(bot_d);
        bot_d.addActionListener(this);
        jpl.add(bot_e);
        bot_e.addActionListener(this);
        jpl.add(bot_c);
        bot_c.addActionListener(this);
        jpl.add(bot_off);
        bot_off.addActionListener(this);
        //setSize(200,280); size不能set了，也不用show()
        //show();
    }
    public void paint(Graphics g)
    {
        super.paint(g);
    }
    /***按鈕事件的傾聽方法****/
    public void actionPerformed(ActionEvent e) //按鈕事件的處理方法
    { 
        int i;
        for (i=0;i<10;i=i+1)
        {
            if (e.getSource()==bot[i])
            {
                if (txt.getText().equals("0")) //強化0的處理
                    txt.setText(Integer.toString(i));
                else 
                    txt.setText(txt.getText()+Integer.toString(i));
                try
                {
                    A=Double.parseDouble(txt.getText());
                }
                catch(NumberFormatException ee){ //處理按錯鍵
                    A=0;
                    txt.setText("Err!");
                }
                return;
            }
        }
        if (e.getSource()==bot_a)
        {
            txt.setText("0");
            B=A;
            A=0;
            op=1;//add
            dot=0;
        }
        else if (e.getSource()==bot_s)
        {
            txt.setText("0");
            B=A;
            A=0;
            op=2;//減
            dot=0;
        }
        else if (e.getSource()==bot_m)
        {
            txt.setText("0");
            B=A;
            A=0;
            op=3;//乘
            dot=0;
        }
        else if (e.getSource()==bot_d)
        {
            txt.setText("0");
            B=A;
            A=0;
            op=4;//除
            dot=0;
        }
        else if (e.getSource()==bot_e)
        {
            txt.setText("=");
            if (op==0) A=B;
            else if (op==1) A=B+A;
            else if (op==2) A=B-A;
            else if (op==3) A=B*A;
            else if (op==4) A=B/A;
            txt.setText(Double.toString(A));
            dot=0;
        }
        else if (e.getSource()==bot_dt)
        {
            txt.setText(txt.getText()+".");
            dot=1;
        }
        else if (e.getSource()==bot_c)
        {
            txt.setText("0");
            dot=0;
            A=0;
            B=0;
        }
        else if (e.getSource()==bot_off)
        {
            //System.exit(0); 不能offㄟ！因為Applet不能隨便跳出去
        }
    }
    public static void main(String args[]) //程式起點
    {
        ui40 app=new ui40(); //畫圖
        JFrame f = new JFrame("兩用程式");
        // To close the application:
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(app);//把Applet 加進去
        f.setSize(400,400);
        app.init();//呼叫init()
        app.start();//呼叫start()
        f.setVisible(true);
    }
}