计算器代码（Java)

package jyh;

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import javax.swing.*;
public class helloa extends Applet implements ActionListener
{
String x="",y="",symbol="";
double answer;
JTextField tfAnswer;
Button button[]=new Button[10];
Button Jia,Jian,Cheng,Chu,ReStart,Pow,Sqrt,Deng,Fu,Point,sin,cos,tan,ln;
public void init()
{
this.setBackground(Color.CYAN);
setLayout(null);
tfAnswer=new JTextField();
tfAnswer.setBounds(5, 5, 265, 30);
tfAnswer.setHorizontalAlignment(JTextField.RIGHT);
tfAnswer.setText("0.");
add(tfAnswer);
SetButton(button[9],"9",95,50,40,30,Color.blue);
SetButton(button[8],"8",50,50,40,30,Color.blue);
SetButton(button[7],"7",5,50,40,30,Color.blue);
SetButton(button[6],"6",95,85,40,30,Color.blue);
SetButton(button[5],"5",50,85,40,30,Color.blue);
SetButton(button[4],"4",5,85,40,30,Color.blue);
SetButton(button[3],"3",95,120,40,30,Color.blue);
SetButton(button[2],"2",50,120,40,30,Color.blue);
SetButton(button[1],"1",5,120,40,30,Color.blue);
SetButton(button[0],"0",5,155,40,30,Color.blue);
SetButton(Jia,"+",140,155,40,30,Color.red);
SetButton(Jian,"-",140,120,40,30,Color.red);
SetButton(Cheng,"*",140,85,40,30,Color.red);
SetButton(Chu,"/",140,50,40,30,Color.red);
SetButton(ReStart,"ReStart",185,50,40,30,Color.red);
SetButton(Pow,"^",185,85,40,30,Color.blue);
SetButton(Sqrt,"sqrt",185,120,40,30,Color.blue);
SetButton(Deng,"=",185,155,40,30,Color.red);
SetButton(Fu,"+/-",50,155,40,30,Color.blue);
SetButton(Point,".",95,155,40,30,Color.blue);
SetButton(sin, "sin", 230, 50, 40, 30, Color.red);
SetButton(cos, "cos", 230, 85, 40, 30, Color.red);
SetButton(tan, "tan", 230, 120, 40, 30, Color.red);
SetButton(ln, "ln", 230, 155, 40, 30, Color.red);
}

public void SetButton(Button name,String symbol,int x,int y,int width,int height,Color color)
{
setLayout(null);
name=new Button(symbol);
name.setBounds(x,y,width,height);
name.setBackground(Color.white);
name.setForeground(color);
name.addActionListener(this);
add(name);
}

public void Equal(String z)
{
if(z.equals("+"))
answer=Double.parseDouble(x)+Double.parseDouble(y);
if(z.equals("-"))
answer=Double.parseDouble(x)-Double.parseDouble(y);
if(z.equals("*"))
answer=Double.parseDouble(x)*Double.parseDouble(y);
if(z.equals("/"))
answer=Double.parseDouble(x)/Double.parseDouble(y);
if(z.equals("^"))
answer=Math.pow(Double.parseDouble(x),Double.parseDouble(y));
if(z.equals("sin"))
answer=Math.sin(Double.parseDouble(x));
if(z.equals("cos"))
answer=Math.cos(Double.parseDouble(x));
if(z.equals("tan"))
answer=Math.tan(Double.parseDouble(x));
if(z.equals("ln"))
answer=Math.log(Double.parseDouble(x));
x=Double.toString(answer);
tfAnswer.setText(x);
y="";symbol="";
}

public void actionPerformed(ActionEvent e) throws IndexOutOfBoundsException
{
if (
e.getActionCommand().equals("0")||
e.getActionCommand().equals("1")||
e.getActionCommand().equals("2")||
e.getActionCommand().equals("3")||
e.getActionCommand().equals("4")||
e.getActionCommand().equals("5")||
e.getActionCommand().equals("6")||
e.getActionCommand().equals("7")||
e.getActionCommand().equals("8")||
e.getActionCommand().equals("9")
)
{
if (symbol.equals(""))
{
x=x+e.getActionCommand();
if (x.startsWith("00"))
{
x=x.substring(1);
}
tfAnswer.setText(x);
}
else
{
y=y+e.getActionCommand();
if (y.startsWith("00"))
{
y=y.substring(1);
}
tfAnswer.setText(y);
}
}

if (e.getActionCommand().equals("."))
{
if (symbol.equals(""))
{
int i=0,j=0;
for (i=0;i<x.length();i++)
{
if (x.charAt(i)=='.')
{
j++;
}
}
if (j==0)
{
x=x+".";
}
tfAnswer.setText(x);
}
else
{
int i=0,j=0;
for (i=0;i<y.length();i++)
{
if (y.charAt(i)=='.')
{
j++;
}
}
if (j==0)
{
y=y+".";
}
tfAnswer.setText(y);
}
}

if (e.getActionCommand().equals("ReStart"))
{
x="";y="";symbol="";
tfAnswer.setText("0.");
}
if (e.getActionCommand().equals("+/-"))
{
if (symbol.equals(""))
{
if(x.substring(0,1).equals("-"))
{
x=x.substring(1);
}
else
{
x="-"+x;
}
tfAnswer.setText(x);
}
else
{
if(y.substring(0,1).equals("-"))
{
y=y.substring(1);
}
else
{
y="-"+y;
}

tfAnswer.setText(y);
}
}

if(e.getActionCommand().equals("sqrt"))
{
if(symbol!="")
{
Equal(symbol);
}
answer=Math.sqrt(Double.parseDouble(x));
x=Double.toString(answer);
tfAnswer.setText(x);
}
if(e.getActionCommand().equals("+"))
{
if(symbol!="")
Equal(symbol);
symbol="+";
}
if(e.getActionCommand().equals("-"))
{
if(symbol!="")
Equal(symbol);
symbol="-";
}
if(e.getActionCommand().equals("*"))
{
if(symbol!="")
Equal(symbol);
symbol="*";
}
if(e.getActionCommand().equals("/"))
{
if(symbol!="")
Equal(symbol);
symbol="/";
}
if(e.getActionCommand().equals("^"))
{
if(symbol!="")
Equal(symbol);
symbol="^";
}
if(e.getActionCommand().equals("sin"))
{
if(symbol!="")
Equal(symbol);
answer=Math.sin(Double.parseDouble(x));
x=Double.toString(answer);
tfAnswer.setText(x);
}
if(e.getActionCommand().equals("ln"))
{
if(symbol!="")
Equal(symbol);
answer=Math.log(Double.parseDouble(x));
x=Double.toString(answer);
tfAnswer.setText(x);
}
if(e.getActionCommand().equals("cos"))
{
if(symbol!="")
Equal(symbol);
answer=Math.cos(Double.parseDouble(x));
x=Double.toString(answer);
tfAnswer.setText(x);
}
if(e.getActionCommand().equals("tan"))
{
if(symbol!="")
Equal(symbol);
answer=Math.tan(Double.parseDouble(x));
x=Double.toString(answer);
tfAnswer.setText(x);
}
if(e.getActionCommand().equals("="))
Equal(symbol);
}
}