在我的基本计算器上添加小数点

Question

我试图在我的程序中添加一个小数点。我设法添加按钮但问题是它没有出现在文本字段上，如果有人可以帮助谢谢。 PS。我不是很擅长在程序中添加评论，如果这困扰任何人，那就不好了。

import java.awt.*;
import java.awt.event.*;
import java.awt.Font;

public class Finals extends java.applet.Applet implements ActionListener {
    TextField txtTotal = new TextField("");
    Button button[] = new Button[10];
    Button divide = new Button("/");
    Button mult = new Button("*");
    Button plus = new Button ("+");
    Button minus = new Button("-");
    Button isequalto = new Button("=");
    Button clear = new Button("Clear");
    double num ,numtemp ;
    int counter;
    String strnum = "",strnumtemp = "" ;
    String op = "";

    public void operation() {
     counter ++;
         if (counter == 1) {
          numtemp = num;
          strnum = "";
          num = 0;
         }else{
          if (op == "+") numtemp += num;
          else if (op == "-") numtemp -= num;
          else if (op == "*") numtemp = numtemp * num;
          else if (op == "/") numtemp = numtemp / num;
          strnumtemp = Double.toString(numtemp);
          txtTotal.setText(strnumtemp);
          strnum = "";
          num = 0;
         }
    }

  public void init() {
     setLayout(null);
     setSize(268,318);
     Font myFont = new Font("Arial",Font.BOLD,15);
     Font bigFont = new Font("Arial",Font.BOLD,20);

// *color Background of components*
     plus.setBackground(Color.black);
     plus.setForeground(Color.white);
     plus.setFont(myFont);
     minus.setBackground(Color.black);
     minus.setForeground(Color.white);
     minus.setFont(bigFont);
     divide.setBackground(Color.black);
     divide.setForeground(Color.white);
     divide.setFont(bigFont);
     isequalto.setBackground(Color.black);
     isequalto.setForeground(Color.white);
     isequalto.setFont(myFont);
     mult.setBackground(Color.black);
     mult.setForeground(Color.white);
     mult.setFont(bigFont);
     clear.setBackground(Color.black);
     clear.setForeground(Color.white);
     clear.setFont(myFont);
     txtTotal.setBackground(Color.darkGray);
     txtTotal.setForeground(Color.white);
     txtTotal.setFont(bigFont);

     for(int i = 0;i <= 9; i ++) {
         button[i] = new Button(String.valueOf(i));
         button[i].setBackground(Color.lightGray);
         button[i].setForeground(Color.black);
     button[i].setFont(myFont);
     }

     button[1].setBounds(0,159,67,53);
     button[2].setBounds(67,159,67,53);
     button[3].setBounds(134,159,67,53);
     button[4].setBounds(0,106,67,53);
     button[5].setBounds(67,106,67,53);
     button[6].setBounds(134,106,67,53);
     button[7].setBounds(0,53,67,53);
     button[8].setBounds(67,53,67,53);
     button[9].setBounds(134,53,67,53);

     for (int i = 1;i <= 9; i ++) {
         add(button[i]);
     }

     txtTotal.setBounds(0,0,267,53);
     add(txtTotal);
     plus.setBounds(201,212,67,106);
     add(plus);
     button[0].setBounds(0,212,134,53);
     add(button[0]);
     minus.setBounds(201,159,67,53);
     add(minus);
     mult.setBounds(201,106,67,53);
     add(mult);
     divide.setBounds(201,53,67,53);
     add(divide);
     isequalto.setBounds(134,212,67,53);
     add(isequalto);
     clear.setBounds(0, 265, 201, 53);
     add(clear);
    }

    public void start() {
     for(int i = 0;i <= 9; i ++) {
         button[i].addActionListener(this);
     }
     plus.addActionListener(this);
     minus.addActionListener(this);
     divide.addActionListener(this);
     mult.addActionListener(this);
     isequalto.addActionListener(this);
     clear.addActionListener(this);
    }

    public void stop() {
     for(int i = 0;i <= 9; i ++) {
         button[i].addActionListener(null);
     }
     plus.addActionListener(null);
     minus.addActionListener(null);
     divide.addActionListener(null);
     mult.addActionListener(null);
     isequalto.addActionListener(null);
     clear.addActionListener(null);
    }

    public void actionPerformed(ActionEvent e) {
        for(int i = 0;i <= 9; i++) {
            if (e.getSource() == button[i]) {
               play(getCodeBase(),i + ".au");
               strnum += Integer.toString(i);
               txtTotal.setText(strnum);
               num = Double.valueOf(strnum).doubleValue();
            }
        }

        if (e.getSource() == plus) {
         operation();
         op = "+";
        }

        if (e.getSource() == minus) {
         operation();
         op = "-";
        }

        if (e.getSource() == divide) {
         operation();
         op = "/";
        }

        if (e.getSource() == mult) {
         operation();
         op = "*";
        }

        if (e.getSource() == isequalto) {

         if (op == "+") numtemp += num;
         else if (op == "-") numtemp -= num;
         else if (op == "*") numtemp = numtemp * num;
         else if (op == "/") numtemp = numtemp / num;

         strnumtemp = Double.toString(numtemp);
         txtTotal.setText(strnumtemp);
         strnumtemp = "";
         numtemp = 0;
         strnum = "";
         num = 0;
         counter = 0;
        }

        if (e.getSource() == clear) {
         txtTotal.setText("0");
         strnumtemp = "";
         numtemp = 0;
         strnum = "";
         num = 0;
         counter = 0;
        }
    }
}