计算器

[java]代码库

package day_01;

import java.awt.BorderLayout;  
import java.awt.Color;  
import java.awt.Container;  
import java.awt.Font;  
import java.awt.GridLayout;  
import java.awt.event.ActionEvent;  
import java.awt.event.ActionListener;  
import java.util.Stack;  
  
import javax.swing.JApplet;  
import javax.swing.JButton;  
import javax.swing.JFrame;  
import javax.swing.JPanel;  
import javax.swing.JTextField;  
  
public class Jsq extends JApplet implements ActionListener  
{   
	 public static void main(String[] args)  
	    {  
	        JFrame frame = new JFrame("Jisuan");  
	        Jsq applet = new Jsq();  
	        frame.getContentPane().add(applet, BorderLayout.CENTER);  
	        applet.init();//applet的init方法  
	        applet.start();//线程开始  
	        frame.setSize(350, 400);//设置窗口大小  
	        frame.setVisible(true);//设置窗口可见  
	    }  
    private static final long serialVersionUID = 1L;  
    private JTextField textField = new JTextField("请输入");  
    String operator = "";//操作  
    String input = "";//输入的 式子  
    boolean flag =  true;  
//  boolean flag1 = true;  
//  boolean flag2 = true;  
    public void init()//覆写Applet里边的init方法  
    {  
        Container C = getContentPane();  
        JButton b[] = new JButton[16];  
        JPanel panel = new JPanel();  
        C.add(textField, BorderLayout.NORTH);  
        C.add(panel,BorderLayout.CENTER);  
        panel.setLayout(new GridLayout(4, 4,5,5));  
        String name[]={"7","8","9","+","4","5","6","-","1","2","3","*","0","C","=","/"};//设置 按钮  
        for(int i=0;i<16;i++)//添加按钮  
        {  
            b[i] = new JButton(name[i]);  
            b[i].setBackground(new Color(192,192,192));  
            b[i].setForeground(Color.BLUE);//数字键 设置为 蓝颜色  
            if(i%4==3)  
                b[i].setForeground(Color.RED);  
            b[i].setFont(new Font("宋体",Font.PLAIN,16));//设置字体格式  
            panel.add(b[i]);  
            b[i].addActionListener(this);  
        }  
        b[13].setForeground(Color.RED);//非数字键，即运算键设置为红颜色  
        b[13].setForeground(Color.RED);  
    }  
    public void actionPerformed(ActionEvent e)   
    {  
        int cnt = 0;  
        String actionCommand = e.getActionCommand();  
        if(actionCommand.equals("+")||actionCommand.equals("-")||actionCommand.equals("*") ||actionCommand.equals("/"))  
            input +=" "+actionCommand+" ";//设置输入，把输入的样式改成 需要的样子  
        else if(actionCommand.equals("C"))  
            input = "";  
        else if(actionCommand.equals("="))//当监听到等号时，则处理 input  
        {  
            input+= "="+compute(input);  
            textField.setText(input);  
            input="";  
            cnt = 1;  
        }  
        else  
            input += actionCommand;//数字为了避免多位数的输入 不需要加空格  
        if(cnt==0)  
        textField.setText(input);  
    }  
    private String compute(String input)//即1237 的 样例  
    {  
        String str[];  
        str = input.split(" ");  
        Stack<Double> s = new Stack<Double>();  
        double m = Double.parseDouble(str[0]);  
        s.push(m);  
        for(int i=1;i<str.length;i++)  
        {  
            if(i%2==1)    
            {    
                if(str[i].compareTo("+")==0)    
                {    
                    double help = Double.parseDouble(str[i+1]);    
                    s.push(help);    
                }    
                    
                if(str[i].compareTo("-")==0)    
                {    
                    double help = Double.parseDouble(str[i+1]);    
                    s.push(-help);    
                }    
                    
                if(str[i].compareTo("*")==0)    
                {    
                    double help = Double.parseDouble(str[i+1]);    
                    double ans = s.peek();//取出栈顶元素    
                    s.pop();//消栈    
                    ans*=help;    
                    s.push(ans);    
                }    
                    
                if(str[i].compareTo("/")==0)    
                {    
                    double help = Double.parseDouble(str[i+1]);    
                    double ans = s.peek();    
                    s.pop();    
                    ans/=help;    
                    s.push(ans);    
                }    
            }    
        }    
        double ans = 0d;    
        while(!s.isEmpty())    
        {    
            ans+=s.peek();    
            s.pop();    
        }    
        String result = String.valueOf(ans);  
        return result;  
    }  
   
  
}