计算器代码

//APPLET
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.*;
public class SZJSQ extends JApplet implements ActionListener
{
boolean i=true;
private JButton num0=new JButton("0");
private JButton num1=new JButton("1");
private JButton num2=new JButton("2");
private JButton num3=new JButton("3");
private JButton num4=new JButton("4");
private JButton num5=new JButton("5");
private JButton num6=new JButton("6");
private JButton num7=new JButton("7");
private JButton num8=new JButton("8");
private JButton num9=new JButton("9");
private JButton zuok=new JButton("(");
private JButton youk=new JButton(")");
private JButton dian=new JButton(".");
private JButton NULL=new JButton("N");
private JButton plu=new JButton("+");
private JButton min=new JButton("-");
private JButton mul=new JButton("x");
private JButton div=new JButton("/");
private JButton equ=new JButton("=");
private JButton cle=new JButton("C");//清除
private JTextField space=new JTextField(30);

public void init()
{
JPanel text=new JPanel();
text.setLayout(new FlowLayout());
text.add(space);
JPanel buttons=new JPanel();
buttons.setLayout(new GridLayout(5,4));
buttons.add(num9);
buttons.add(num8);
buttons.add(num7);
buttons.add(plu);
buttons.add(num6);
buttons.add(num5);
buttons.add(num4);
buttons.add(min);
buttons.add(num3);
buttons.add(num2);
buttons.add(num1);
buttons.add(mul);
buttons.add(num0);
buttons.add(cle);
buttons.add(equ);
buttons.add(div);
buttons.add(zuok);
buttons.add(youk);
buttons.add(dian);
buttons.add(NULL);
(num9).addActionListener(this);
(num8).addActionListener(this);
(num7).addActionListener(this);
(num6).addActionListener(this);
(num5).addActionListener(this);
(num4).addActionListener(this);
(num3).addActionListener(this);
(num2).addActionListener(this);
(num1).addActionListener(this);
(num0).addActionListener(this);
(plu).addActionListener(this);
(min).addActionListener(this);
(mul).addActionListener(this);
(div).addActionListener(this);
(equ).addActionListener(this);
(cle).addActionListener(this);
(zuok).addActionListener(this);
(youk).addActionListener(this);
(dian).addActionListener(this);
setLayout(new BorderLayout());
add("North",text);
add("South",buttons);
space.setText("0");
}

public void actionPerformed(ActionEvent e)
{

if(e.getSource()==num9)
{
if(i==true)
{
space.setText("9");
i=false;
}
else space.setText(space.getText()+'9');
}
if(e.getSource()==num8)
{
if(i==true)
{
space.setText("8");
i=false;
}
else space.setText(space.getText()+'8');
}
if(e.getSource()==num7)
{
if(i==true)
{
space.setText("7");
i=false;
}
else space.setText(space.getText()+'7');
}
if(e.getSource()==num6)
{
if(i==true)
{
space.setText("6");
i=false;
}
else space.setText(space.getText()+'6');
}
if(e.getSource()==num5)
{
if(i==true)
{
space.setText("5");
i=false;
}
else space.setText(space.getText()+'5');
}
if(e.getSource()==num4)
{
if(i==true)
{
space.setText("4");
i=false;
}
else space.setText(space.getText()+'4');
}
if(e.getSource()==num3)
{
if(i==true)
{
space.setText("3");
i=false;
}
else space.setText(space.getText()+'3');
}
if(e.getSource()==num2)
{
if(i==true)
{
space.setText("2");
i=false;
}
else space.setText(space.getText()+'2');
}
if(e.getSource()==num1)
{
if(i==true)
{
space.setText("1");
i=false;
}
else space.setText(space.getText()+'1');
}
if(e.getSource()==num0)
{
if(i==true)
{
space.setText("0");
i=false;
}
else space.setText(space.getText()+'0');
}
if(e.getSource()==zuok)
{
if(i==true)
{
space.setText("(");
i=false;
}
else space.setText(space.getText()+'(');
} if(e.getSource()==youk)
{
if(i==false)
space.setText(space.getText()+')');
}
if(e.getSource()==dian)
{
if(i==false)
space.setText(space.getText()+'.');
}
if(e.getSource()==plu)
{
space.setText(space.getText()+'+');
i=false;
}
if(e.getSource()==min)
{
space.setText(space.getText()+'-');
i=false;
}
if(e.getSource()==mul)
{
space.setText(space.getText()+'*');
i=false;
}
if(e.getSource()==div)
{
space.setText(space.getText()+'/');
i=false;
}
if(e.getSource()==equ)
{
space.setText(String.valueOf(Calculator(space.getText())));
i=true;
}
if(e.getSource()==cle)
{
space.setText("0");
i=true;
}

}

public double Calculator(String f)//科学计算
{
int i=0,j=0,k;
char c;
StringBuffer s=new StringBuffer();
s.append(f);
s.append('=');
String formula=s.toString();
char[] anArray;
anArray=new char[50];
Stack mystack=new Stack();
while(formula.charAt(i)!='=')
{
c=formula.charAt(i);
switch(c)
{
case '(': mystack.push(new Character(c));
i++;
break;
case ')':
while(mystack.peek().charValue()!='(')
{
anArray[j++]=mystack.pop().charValue();
}
mystack.pop();
i++;
break;
case '+':
case '-':
while(!mystack.empty()&&mystack.peek().charValue()!='(')
{
anArray[j++]=mystack.pop().charValue();

}
mystack.push(new Character(c));
i++;
break;
case '*':
case '/':
while(!mystack.empty()&&(mystack.peek().charValue()=='*'||mystack.peek().charValue()=='/'))
{
anArray[j++]=mystack.pop().charValue();
}
mystack.push(new Character(c));
i++;
break;
case' ': i++;
break;
default: while((c>='0'&&c<='9')||c=='.')
{
anArray[j++]=c;
i++;
c=formula.charAt(i);
}
anArray[j++]='#';
break;
}
}
while(!(mystack.empty()))
anArray[j++]=mystack.pop().charValue();

i=0;
int count;
double a,b,d;
Stack mystack1 =new Stack();
while(i {
c=anArray[i];
switch(c)
{
case '+':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
d=b+a;
mystack1.push(new Double(d));
i++;
break;
case '-':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
d=b-a;
mystack1.push(new Double(d));
i++;
break;
case '*':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
d=b*a;
mystack1.push(new Double(d));
i++;
break;
case '/':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
if(a!=0)
{
d=b/a;
mystack1.push(new Double(d));
i++;
}
else
{
System.out.println("Error!");
}
break;
default:
d=0;count=0;
while((c>='0'&&c<='9'))
{
d=10*d+c-'0';
i++;
c=anArray[i];
}
if(c=='.')
{
i++;
c=anArray[i];
while((c>='0'&&c<='9'))
{
count++;
d=d+(c-'0')/Math.pow(10,count);
i++;
c=anArray[i];
}
}
if(c=='#')
mystack1.push(new Double(d));
i++;
break;
}
}
return(mystack1.peek().doubleValue());
}
}

import java.awt.*; //引入AWT包
import java.awt.event.*; //引入awt.event包
import javax.swing.*; //引入javax.swing包
public class JSQ extends JFrame implements ActionListener //事件监听器为接口
{
private String name[] =
{"0","1", "2","+","3","4","5","-","6","7","8","*","9",".","=","/"}; //创建按钮数组
private String extend[] =
{"x^2","ln","back","sin","cos","tan","sqrt","关闭","清空"}; String s="";
int flag=0;
double x;
final double pi = 3.14159265358979323846;
private JButton button[] = new JButton[name.length]; //创建按钮数组

private JButton button1[] = new JButton[extend.length]; //创建功能键按钮数组

JLabel dis_show = new JLabel("结果:");
JTextField w = new JTextField(12); //文本长度为12
public JSQ2() //构造函数
{
super("计算机");
setSize(200,290);
Container c = getContentPane();
c.setLayout(new GridLayout(2,1,0,0));
JPanel result = new JPanel();
result.add(dis_show);
result.add(w);
for(int i= 0;i {
button1[i] = new JButton(extend[i]);
result.add(button1[i]);
}
JPanel border = new JPanel();
for(int i= 0;i {
button[i] = new JButton(name[i]);
border.add(button[i]);
}
c.add(result);
c.add(border);
for(int i= 0;i {
button[i].addActionListener(this);
}
for(int i= 0;i {
button1[i].addActionListener(this);
}
show();
}
public void actionPerformed(ActionEvent e)
{
if (e.getSource()==button[3])
{
x=Double.parseDouble(s);

flag=1;
w.setText("");
s="";
}
else if (e.getSource()==button[7])
{
x=Double.parseDouble(s);
flag=2;
w.setText("");
s="";
}
else if (e.getSource()==button[11])
{
x=Double.parseDouble(s);
flag=3;
w.setText("");
s="";
}
else if (e.getSource()==button[15])
{
x=Double.parseDouble(s);
flag=4;
w.setText("");
s="";
}
else if (e.getSource()==button[14])
{
switch(flag)
{
case 1:
{

x=x+Double.parseDouble(s);
String s=String.valueOf(x);
w.setText(s);
break;
}
case 2:
{
x=x-Double.parseDouble(s);
String s=String.valueOf(x);
w.setText(s);
break;
}
case 3:
{
x=x*Double.parseDouble(s);
String s=Double.toString(x);
w.setText(s);
break;
}
case 4:
{
if(Double.parseDouble(s)==0)
{
w.setText("除数不能为0");
break;
}
x=x/Double.parseDouble(s);
String s=String.valueOf(x);
w.setText(s);
break;
}
}
}
else if(e.getSource()==button1[2])
{
StringBuffer str = new StringBuffer(w.getText());
int n=str.length();
int m=n-1;
s = String.valueOf(str.delete(m,n));
w.setText(s);
}
else if(e.getSource()==button1[8])
{
w.setText("");
s="";
flag=0;
}
else if(e.getSource()==button1[0])
{
x=Double.parseDouble(s);
x=x*x;
String s=String.valueOf(x);
w.setText(s);
}
else if(e.getSource()==button1[1])
{
x=Math.log(Double.parseDouble(s));
String s=String.valueOf(x);
w.setText(s);
}
else if(e.getSource()==button1[3])
{
x=Math.sin(Double.parseDouble(s)*pi/180);
String s=String.valueOf(x);
w.setText(s);
}
else if(e.getSource()==button1[6])
{
x=Math.sqrt(Double.parseDouble(s));
String s=String.valueOf(x);
w.setText(s);
}
else if(e.getSource()==button1[4])
{
x=Math.cos(Double.parseDouble(s)*pi/180);
String s=String.valueOf(x);
w.setText(s);
}
else if(e.getSource()==button1[5])
{
x=Math.tan(Double.parseDouble(s)*pi/180);
String s=String.valueOf(x);
w.setText(s);
}
else if(e.getSource()==button1[7])
{
System.exit(0);
}
else
{
s=s+e.getActionCommand();
w.setText(s);
}
}
public static void main(String[] args)
{
JSQ2 bun = new JSQ();
bun.addWindowListener(new WindowAdapter()
{
public void windowListener(WindowEvent e)
{
System.exit(0);
}
});
}
}
太多啦，懒得解释啦！总的来说就是先创建数组按钮，然后放入面板，面板再加入FRAME，然后实现监听器的方法（按钮功能）！其中要用到布局管理器，具体查看API！
JAVA版本的