一个简单的计算器

[java]代码库

package jisuanqi;
import java.awt.*;
import java.awt.event.*;

public class Calculator implements ActionListener{
private double data1=0.0,data2=0.0;
private String t_content;
boolean number=false;

//key用来标示用户所按下的按钮即加减乘除
//key为0标示+，为1表示-，为2表示*，为3表示/
short key=-1;

//pkey的取值为-1~5
//pkey为-1表示第一次按下=按钮，为5说明不是第一次按下=按钮
//pkey为其他值0,1,2,3时分别代表+，-,*，/
short pkey=-1;

Frame frame=new Frame("我的计算器");//定义标题为计算器的窗体
TextField textfield=new TextField(30);//定义计算器

//定义backspace,ce,c0按钮
Button backspace=new Button("Backspace");
Button ce=new Button("CE");
Button c0=new Button("C");

//定义面板，其中backspace,ce,c0按钮和计算机兰textfeild放在面板p1中
//其余按钮放在面板p2中
Panel p1=new Panel();
Panel p2=new Panel();

//定义界面上的按钮数组，即除去backspace,ce,c0按钮的所有按钮
String names[]={"7","8","9","/","sqrt","4","5","6","*","%","1","2","3","-","1/x","0","+/-",".","+","="};
Button bb[]=new Button[names.length];

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

public void go(){
frame.setSize(500,300);
frame.setLayout(new BorderLayout());
Font fonts=new Font("草体_GB2312",Font.PLAIN,12); // 第一页

//设置面板p1的字体和布局管理类型，将textfeild对象添加到面板中
p1.setFont(fonts);
p1.setLayout(new GridLayout(2,1,5,10));
textfield.setFont(fonts);
p1.add(textfield,null);

//backspace,ce,c0按钮注册addActionListener方法
backspace.addActionListener(this);
ce.addActionListener(this);
c0.addActionListener(this);

//将backspace,ce,c0按钮添加到p1面板中
p1.add(backspace,null);
p1.add(ce,null);
p1.add(c0,null);

//设置面板p2的布局管理器类型为GridLayout
p2.setLayout(new GridLayout(4,5,5,5));

//为按钮组中的按钮注册addActionListener方法
for(int i=0;i<names.length;i++){
bb[i]=new Button(names[i]);
p2.add(bb[i]);
bb[i].addActionListener(this);
}

//设置面板p1和面板p2在窗体中的位置
//面板p1在窗体的North方向，面板p2在窗体的South方向
frame.add(p1,BorderLayout.NORTH);
frame.add(p2,BorderLayout.SOUTH);
frame.setVisible(true);

//当单击关闭按钮时退出系统
frame.addWindowListener(new WindowAdapter(){
 public void windowClosing(WindowEvent e){
 System.exit(0);
 }
 });
}
 public void actionPerformed(ActionEvent ae){
 String s; 
//通过ActionEvent类的getActionCommand()方法，得出动作是由哪个按钮触发的。 //第二页
 s=ae.getActionCommand();

//用户单击一次，计算栏里便去掉一个字符
//先将计算栏里的字符清空，再添加除最好一个字符的字符串
 if(s.equals("Backspace")&&number){
 t_content=textfield.getText();
 textfield.setText("");

for(int i=0;i<t_content.length()-1;i++){
 char c=t_content.charAt(i);
 textfield.setText(textfield.getText()+c);
 }
}

//用户单击的是CE按钮，计算栏清空
if(s.equals("CE")){
 textfield.setText("");
number=false;
}

//用户单击的是C按钮
if(s.equals("C")){
 textfield.setText("");
data1=data2=0.0;
number=false;
}

//用户单击的是sqrt按钮，其中负数不能被开方
if(s.equals("sqrt")&&number){
 t_content=textfield.getText();
 if(t_content.charAt(0)=='-'){
 textfield.setText("负数不能被开方");
 number=false;
 }else{
 textfield.setText(Double.toString(java.lang.Math.sqrt(Double.parseDouble(t_content))));
 }
}

//用户单击的是1/x求倒数按钮，求倒数时分母不能为0
if(s.equals("1/x") && number){
 t_content=textfield.getText();
if(t_content.equals("0")){ //第三页 
textfield.setText("零不能求倒数");
 number=false;
}else{
 textfield.setText(Double.toString(1/Double.parseDouble(t_content)));
 }
}

//用户单击的是%按钮
if(s.equals("%")&&number){
 if(data2==0){
 t_content=textfield.getText();
 textfield.setText(t_content);
}else{
 boolean g=false;
 for(int i=0;i<textfield.getText().length();i++)
 if('.'==textfield.getText().charAt(i)){
 g=true;
 break;
}

//如果是Double 数，除100
if(g=true){
 double dtemp=Double.parseDouble(textfield.getText());
 dtemp=dtemp/100.0;
 textfield.setText(Double.toString(dtemp));
 }

//如果是int数但能被100整除，则去掉末尾两个0
else{
 if(Integer.parseInt(textfield.getText())%100==0){
 int itemp=Integer.parseInt(textfield.getText());
 itemp/=100;
 textfield.setText(Integer.toString(itemp));
 }
 
//如果是int数，但不能被100整除，则按Double数处理
else{
 double dtemp=Double.parseDouble(textfield.getText());
 dtemp=dtemp/100.0;
 textfield.setText(Double.toString(dtemp));
 }
 }
} //第四页

}

 //对正负数字的处理
 if(s.equals("+/-")){
 t_content=textfield.getText();
 if(t_content.charAt(0)=='-'){
 textfield.setText("");
 String content;
 for(int i=1;i<t_content.length();i++){
 textfield.setText(textfield.getText()+t_content.charAt(i));
 }
}else{
 textfield.setText("-"+t_content);
 }
 }
 
 //所按下的按钮为+按钮
if(s.equals("+")){
 switch(pkey){
 case 0:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 1:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 2:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 3:
 if(textfield.getText().equals("0")){
 textfield.setText("除数不能为零");
 number=false;
 }else{
 key=-1;
 data2/=data1;
 textfield.setText(Double.toString(data2));
 break;
 }
 default:
 data2=Double.parseDouble(textfield.getText());
}
 pkey=key=0;
 textfield.setText("");
} 
 //第五页

 //所按下的按钮为-按钮

if(s.equals("-")){
 switch(pkey){
 case 0:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 1:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 2:
 data2+=Double.parseDouble(textfield.getText());
 break;
 
 case 3:
 if(textfield.getText().equals("0")){
 textfield.setText("除数不能为零");
 number=false;
 }else{
 key=-1;
 data2/=data1;
 textfield.setText(Double.toString(data2));
 break;
 }
 default:
 data2=Double.parseDouble(textfield.getText());
 }
 pkey=key=1;
 textfield.setText("");
 } 

 //所按下的按钮为*按钮
 if(s.equals("*")){
 switch(pkey){
 case 0:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 1:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 2:
 data2+=Double.parseDouble(textfield.getText());
 break;
 
 case 3:
 if(textfield.getText().equals("0")){ // 第六页
 textfield.setText("除数不能为零");
 number=false;
 }else{
 key=-1;
 data2/=data1;
 textfield.setText(Double.toString(data2));
 break;
 }
 default:
 data2=Double.parseDouble(textfield.getText());
 }
 pkey=key=2;
 textfield.setText("");
 } 

 //所按下的按钮为/按钮 
 if(s.equals("/")){
 switch(pkey){
 case 0:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 1:
 data2+=Double.parseDouble(textfield.getText());
 break;
 case 2:
 data2+=Double.parseDouble(textfield.getText());
 break;
 
 case 3:
 if(textfield.getText().equals("0")){ 
 textfield.setText("除数不能为零");
 number=false;
 }else{
 key=-1;
 data2/=data1;
 textfield.setText(Double.toString(data2));
 break;
 }
 default:
 data2=Double.parseDouble(textfield.getText());
 }
 pkey=key=3;
 textfield.setText("");
 } //第七页

//所按下的按钮为=，求结果 
 if(s.equals("=")&&number){

 //如果不是第一次按下=按钮
 if(pkey==5){
 switch(pkey){
 case 0:
 data2+=data1;
 textfield.setText(Double.toString(data2));
 break;
 case 1:
 data2-=data1;
 textfield.setText(Double.toString(data2));
 break;
 case 2:
 data2*=data1;
 textfield.setText(Double.toString(data2));
 break;
 case 3:
 if(textfield.getText().equals("0")){ 
 textfield.setText("除数不能为零");
 number=false;
 }else{
 
 data2/=data1;
 textfield.setText(Double.toString(data2));
 break;
 }
 }
 }

 //如果是第一次按下=按钮
 else{
 data1=Double.parseDouble(textfield.getText());
 switch(key){
 case 0:
 key=-1;
 data2+=Double.parseDouble(textfield.getText());
 textfield.setText(Double.toString(data2));
 break;

 case 1:
 key=-1;
 data2-=Double.parseDouble(textfield.getText());
 textfield.setText(Double.toString(data2)); //第八页
 break;
 case 2:
 key=-1;
 data2*=Double.parseDouble(textfield.getText());
 textfield.setText(Double.toString(data2)); 
 break;
 case 3:
 if(textfield.getText().equals("0")){ 
 textfield.setText("除数不能为零");
 number=false;
 }else{
 key=-1;
 data2/=Double.parseDouble(textfield.getText());
 textfield.setText(Double.toString(data2));
 break;
 }
 }
 }
 pkey=5;
 }

 //按下的按钮时数字按钮
 else{
 switch(s.charAt(0)){
 case'0':
 case'1':
 case'2':
 case'3':
 case'4':
 case'5':
 case'6':
 case'7':
 case'8':
 case'9':
 number=true;
 textfield.setText(textfield.getText()+s);
 break;
 //对.的处理
 case'.':
 t_content=textfield.getText();
 boolean g=false; //第九页
 //对计算机栏中的数据进行检验
 //如果其中有小数点，则用户单击该按钮时不在添加小数点
 for(int i=0;i<t_content.length();i++){
 if(t_content.charAt(i)=='.'){
 g=true;
 break;
 }
 }

 //数据中已经有小数点
 if(g==true)
 break;
 // 数据中没有小数点，当用户单击小数点时添加小数点
 if(g==false)
 textfield.setText(t_content+".");
 }
 }
 }

private String Integer(String string) {
 // TODO Auto-generated method stub
 return null;
 }
 }