请高手帮我看看这个计算器程序为什么运行后不能输入数字谢谢了~~
import java.awt.Button;
import java.awt.CheckboxMenuItem;
import java.awt.GridLayout;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.JTextField;


public class Calculator {

GridLayout gl1, gl2, gl3;

Panel p0, p1, p2, p3;

JTextField tf1;

TextField tf2;

Button b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, b10, b11, b12, b13, b14,
b15, b16, b17, b18, b19, b20, b21, b22, b23, b24, b25, b26;

StringBuffer str;

double x, y;

int z;

static double m;

public Calculator() {
MenuItem m31 = new MenuItem( "帮助主题 ");
MenuItem m32 = new MenuItem( "关于计算器 ");
gl1 = new GridLayout(1, 4, 10, 0);
gl2 = new GridLayout(4, 1, 0, 15);
gl3 = new GridLayout(4, 5, 10, 15);
tf1 = new JTextField(27);
tf2 = new TextField(10);
p0 = new Panel();
p1 = new Panel();
p2 = new Panel();
p3 = new Panel();
str = new StringBuffer();
MenuItem m11 = new MenuItem( "复制 ");
MenuItem m12 = new MenuItem( "粘贴 ");
MenuItem m13 = new MenuItem( "退出 ");
MenuItem m23 = new MenuItem( "数字分组 ");
Menu m1 = new Menu( "编辑 ");

Menu m2 = new Menu( "查看 ");
Menu m3 = new Menu( "帮助 ");
CheckboxMenuItem m22 = new CheckboxMenuItem( "科学 ");
MenuItem m21 = new MenuItem( "标准 ");
JFrame f = new JFrame( "计算器 ");
JTextField tf = new JTextField(20);
MenuBar mb = new MenuBar();
tf1.setHorizontalAlignment(JTextField.RIGHT);
tf1.setEnabled(false);
tf1.setText( "0 ");
tf2.setEditable(false);
b0 = new Button( "Backspace ");
b0.addActionListener(new Bt());
b1 = new Button( "CE ");
b1.addActionListener(new Bt());
b2 = new Button( "C ");
b2.addActionListener(new Bt());
b3 = new Button( "MC ");
b3.addActionListener(new Bt());
b4 = new Button( "MR ");
b4.addActionListener(new Bt());
b5 = new Button( "MS ");
b5.addActionListener(new Bt());
b6 = new Button( "M+ ");
b6.addActionListener(new Bt());
b7 = new Button( "7 ");
b7.addActionListener(new Bt());
b8 = new Button( "8 ");
b8.addActionListener(new Bt());
b9 = new Button( "9 ");
b9.addActionListener(new Bt());
b10 = new Button( "/ ");
b10.addActionListener(new Bt());
b11 = new Button( "sqrt ");

b11.addActionListener(new Bt());
b12 = new Button( "4 ");
b12.addActionListener(new Bt());
b13 = new Button( "5 ");
b13.addActionListener(new Bt());
b14 = new Button( "6 ");
b14.addActionListener(new Bt());
b15 = new Button( "* ");

b15.addActionListener(new Bt());
b16 = new Button( "% ");

b16.addActionListener(new Bt());
b17 = new Button( "1 ");

b17.addActionListener(new Bt());
b18 = new Button( "2 ");

b18.addActionListener(new Bt());
b19 = new Button( "3 ");

b19.addActionListener(new Bt());
b20 = new Button( "- ");

b20.addActionListener(new Bt());
b21 = new Button( "1/X ");

b21.addActionListener(new Bt());
b22 = new Button( "0 ");

b22.addActionListener(new Bt());
b23 = new Button( "+/- ");

b23.addActionListener(new Bt());
b24 = new Button( ". ");

b24.addActionListener(new Bt());
b25 = new Button( "+ ");

b25.addActionListener(new Bt());
b26 = new Button( "= ");
b26.addActionListener(new Bt());
f.setMenuBar(mb);

mb.add(m1);
mb.add(m2);
mb.setHelpMenu(m3);

m1.add(m11);
m1.add(m12);
m1.addSeparator();
m1.add(m13);

mb.add(m1);
mb.add(m2);
mb.setHelpMenu(m3);

m2.add(m21);

m2.add(m22);

m2.addSeparator();
m2.add(m23);

m3.add(m31);
m3.addSeparator();
m3.add(m32);
f.setSize(300, 300);
f.setVisible(true);
p0.add(tf1);
p0.setBounds(10, 25, 300, 40);
p1.setLayout(gl1);
p1.add(tf2);
p1.add(b0);
p1.add(b1);
p1.add(b2);
p1.setBounds(10, 65, 300, 25);
p2.setLayout(gl2);
p2.add(b3);
p2.add(b4);
p2.add(b5);
p2.add(b6);
p2.setBounds(10, 110, 40, 150);
p3.setLayout(gl3);
p3.add(b7);
p3.add(b8);
p3.add(b9);
p3.add(b10);
p3.add(b11);
p3.add(b12);
p3.add(b13);
p3.add(b14);
p3.add(b15);
p3.add(b16);
p3.add(b17);
p3.add(b18);
p3.add(b19);
p3.add(b20);
p3.add(b21);
p3.add(b22);

p3.add(b23);
p3.add(b24);
p3.add(b25);
p3.add(b26);
p3.setBounds(60, 110, 250, 150);



f.setLayout(null);
f.add(p0);
f.add(p1);
f.add(p2);
f.add(p3);

f.addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e1) {
System.exit(0);
}
});

f.setSize(350, 350);
f.setVisible(true);
}




class Bt implements ActionListener {


public void actionPerformed(ActionEvent e2) {


if (e2.getSource() == b1) {
tf1.setText( "0 ");
str.setLength(0);
}

else if (e2.getSource() == b25) {
x = Double.parseDouble(tf1.getText().trim());
str.setLength(0);
y = 0d;
z = 0;

}

else if (e2.getSource() == b26) {
str.setLength(0);
switch (z) {
case 0:
tf1.setText( " " + (x + y));
break;
}
} else if (e2.getSource() == b24) {
if (tf1.getText().trim().indexOf( ". ") != -1) {

} else {
if (tf1.getText().trim().equals( "0 ")) {
str.setLength(0);
tf1.setText((str
.append( "0 " + e2.getActionCommand()))
.toString());
} else if (tf1.getText().trim().equals( " ")) {
} else {

tf1.setText(str.append(e2.getActionCommand())
.toString());
}
}

y = 0d;
}

}


}


public static void main(String args[]) {
Calculator c = new Calculator();
}
}


[解决办法]
你的程序还没有写全呢
Bt类中其他按钮的动作代码你还没有些呢
在public void actionPerformed(ActionEvent e2)
中再加一个
else {
String a=((Button)e2.getSource()).getLabel();
tf1.setText(a);}
}

但是你的‘＋’功能写的有欠缺，y没有被赋值，所以完不成＋的功能
你再好好补充一下