counter.java

java语言开发的计算器

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Counter implements ActionListener{
	Frame f = new Frame("计算器");
	Panel p = new Panel(); 
	TextField  tf1 = new TextField(20);
	Button[] b = new Button[21];
	String[] s = {"退格","CE","C","/",
					"7","8","9","*",
					"4","5","6","-",
					"1","2","3","+",
					"0","+/-",".","="};
	double d1;
	double d2;
	double result;
	String operator;
	boolean flag1;
	boolean i = false;
	
	//创建菜单
	MenuBar mb = new MenuBar(); 
	Menu m1 = new Menu("Help");
	MenuItem mi1 = new MenuItem("about as");
	MenuItem mi2 = new MenuItem("quit");
	
	public Counter(){
		f.setMenuBar(mb);
		mb.add(m1); 
		mi1.addActionListener(this);
		mi2.addActionListener(this); 
		m1.add(mi1);
		m1.addSeparator();
		m1.add(mi2); 
	
		tf1.setForeground(Color.black);
		tf1.setFont(new Font("Arial Black",1,20));
	
		for(int i=1;i<21;i++){
			b[i] = new Button(s[i-1]);
			b[i].setFont(new Font("仿宋",1,15));
			b[i].addActionListener(this);
		}
	
		p.setLayout(new GridLayout(5,4,3,3));
		p.setBackground(Color.LIGHT_GRAY);
	
		for(int i=1;i<21;i++){	 
			p.add(b[i]);
			b[i].setBackground(new Color(20,130,180));
			b[i].setForeground(Color.yellow);
		}
		for(int i=1;i<4;i++)  {
			b[i].setBackground(new Color(120,180,170));
			b[i].setForeground(Color.blue);
		}
		for(int i=1;i<=4;i++){	  
			b[i*4].setBackground(new Color(120,180,170));
			b[i*4].setForeground(Color.red);
		}
		
		b[20].setBackground(Color.red);
		f.setLayout(new BorderLayout(3,3));
		f.add("North",tf1);
		f.add("Center",p);
		f.setSize(300,200);
		f.setLocation(300,300);
		f.setBackground(Color.LIGHT_GRAY);
		f.setResizable(false);
		f.setVisible(true);
	
		f.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e){
				System.exit(0);
			}
		});
	}
	
	public void actionPerformed(ActionEvent e){
		//获得按扭信息
		String s = e.getActionCommand();
		String s1 = tf1.getText();
		if(s=="0"||s=="1"||s=="2"||s=="3"||s=="4"||s=="5"||s=="6"||s=="7"||s=="8"||s=="9"){
			if(flag1){
				tf1.setText(s);
				flag1 = false;
			}else{
				s1 = s1+s;
				tf1.setText(s1);
			}          	
		}else if(s =="."){
			int j = s1.indexOf(".");
			if(j ==-1){
				s1 = s1 + s;
				tf1.setText(s1);
			}
		}else if(s=="+"|| s=="-"||s=="*"||s=="/"){
			operator = s;
			d1 = Double.parseDouble(s1);
			flag1 = true;
			if(operator=="+"){
				//实现连加
				if(i){
					d1=0;
					i = false;
				}else{
					result += d1;	
				}
				tf1.setText(result+"");	
			}else if(operator=="-"){
				d2 = Double.parseDouble(s1);
				result = d1 - d2;
			}else if(operator=="*"){
				d2 = Double.parseDouble(s1);
				result = d1 * d2;
			}else{
				d2 = Double.parseDouble(s1);
				result = d1 / d2;
			}
			
		}else if(s=="="){
			d2 = Double.parseDouble(s1);
			if(operator=="+"){
				result += d2;
				i = true;
			}else if(operator=="-"){
				result = d1 - d2;
			}else if(operator=="*"){
				result = d1 * d2;
			}else{
				result = d1 / d2;
			}
			//tf1.setText(result+"");//这样处理会降低效率
			tf1.setText(new Double(result).toString());//封装
		}else if(s=="退格"){          
			if(!s1.equals("")){
				s1 = s1.substring(0,s1.length()-1);
				tf1.setText(s1);
			}
		}else if(s=="+/-"){
			double d=Double.parseDouble(s1);
			d = -d;
			tf1.setText(String.valueOf(d));//封装另一种写法
		}else if(s=="C"){
			tf1.setText("");
			flag1 = true;
		}else if(s=="CE"){
			tf1.setText("");
			d1 = 0;
			d2 = 0;
			result = 0;
			flag1 = true;
		}else if(s=="quit"){
			System.exit(0);
		}else{
			JOptionPane.showMessageDialog(f,"angela 1.0","about",JOptionPane.QUESTION_MESSAGE);//swing
		}
	}
	public static void main(String args[]){ 	          
		new Counter();
	}
}