用java做一个简单的计算器
我是java初学者，尝试做一个简单的计算器，但运行会产生异常，而且得不到运算结果，请各位高手指点...程序如下：
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.border.*;
class 布局 extends Frame implements ActionListener
{ TextField text;  
  Button button1,button2,button3,button4;
  Button button5,button6,button7,button8;
  Button button9,button10,button11,button12;
  Button button13,button14,button15,button16;
  Panel panel1,panel2;
  Box boxv1,boxv2,boxv3,boxv4;
  Box boxh1,boxh2,boxh3,boxh4;
  Font font=new Font("黑体",Font.BOLD,15);
  布局()
  { setTitle("计算器");
  text=new TextField("0",10);
  Button button1=new Button("7");
  button2=new Button("4");
  button3=new Button("1");
  button4=new Button("0");
  button5=new Button("8");
  button6=new Button("5");
  button7=new Button("2");
  button8=new Button("c");
  button9=new Button("9");
  button10=new Button("6");
  button11=new Button("3");
  button12=new Button("=");
  button13=new Button("+");
  button14=new Button("-");
  button15=new Button("*");
  button16=new Button("/");
  button1.setForeground(Color.blue);
  button2.setForeground(Color.blue);
  button3.setForeground(Color.blue);
  button4.setForeground(Color.blue);
  button5.setForeground(Color.blue);
  button6.setForeground(Color.blue);
  button7.setForeground(Color.blue);
  button8.setForeground(Color.red);
  button9.setForeground(Color.blue);
  button10.setForeground(Color.blue);
  button11.setForeground(Color.blue);
  button12.setForeground(Color.red);
  button13.setForeground(Color.red);
  button14.setForeground(Color.red);
  button15.setForeground(Color.red);
  button16.setForeground(Color.red);
  button1.setFont(font);
  button2.setFont(font);
  button3.setFont(font);
  button4.setFont(font);
  button5.setFont(font);
  button6.setFont(font);
  button7.setFont(font);
  button8.setFont(font);
  button9.setFont(font);
  button10.setFont(font);
  button11.setFont(font);
  button12.setFont(font);
  button13.setFont(font);
  button14.setFont(font);
  button15.setFont(font);
  button16.setFont(font);
  Panel panel1=new Panel();
  Panel panel2=new Panel();
  panel1.setBackground(Color.blue);
  panel2.setBackground(Color.blue);
  boxv1=Box.createVerticalBox();
  boxv2=Box.createVerticalBox();
  boxv3=Box.createVerticalBox();
  boxv4=Box.createVerticalBox();
  boxv1.add(button1);
  boxv1.add(Box.createVerticalStrut(8));
  boxv1.add(button2);
  boxv1.add(Box.createVerticalStrut(8));
  boxv1.add(button3);
  boxv1.add(Box.createVerticalStrut(8));
  boxv1.add(button4);
  boxv2.add(button5);
  boxv2.add(Box.createVerticalStrut(8));
  boxv2.add(button6);
  boxv2.add(Box.createVerticalStrut(8));