简单计算器

package com.cal;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class cal extends JFrame implements ActionListener{
        private static JTextField tf = new JTextField();
        private static     JButton[] btn= new JButton[17];  //17 buttons 
        private double num1=0.0 ,num2=0.0,result=0.0;
        String opt = null;
        
        //consduct method
        public cal(){
            //使用父类构造方法方法子类构造方法的第一行
            super("CalculatorHaha");
            
        }
    public void launch(){
        Font f = new Font("f",Font.BOLD,20);
        tf.setFont(f);
        tf.setEditable(false);
        
        
        GridBagLayout gb = new GridBagLayout();
        setBounds(700,100,300,310);
        
        setLayout(gb);
    
    
        String[] str={"7","8","9","/","4","5","6","*","1","2","3","-",".","0","=","+"};
        
        
        GridBagConstraints c = new GridBagConstraints();
        
        //set 
        c.weightx = 0.2;
        c.weighty = 0.2; 
        
        
        c.gridy = 0;
        c.gridwidth = 3 ;
        c.fill =GridBagConstraints.BOTH;
        gb.setConstraints(tf, c);
        add(tf);
    
        c.gridx = GridBagConstraints.RELATIVE;
        c.gridwidth = 1 ;
        btn[16] = new JButton("CE");  //
        gb.setConstraints(btn[16], c);
        add(btn[16]);
        
        
        c.gridy = 1 ;
        for(int i = 0;i<4;i++){
            btn[i] = new JButton(str[i]);
            gb.setConstraints(btn[i], c);
            add(btn[i]);    
        }
        
        c.gridy = 2 ;
        for(int i = 4;i<8;i++){
            btn[i] = new JButton(str[i]);
            gb.setConstraints(btn[i], c);
            add(btn[i]);    
        }
        
        c.gridy = 3 ;
        for(int i = 8;i<12;i++){
            btn[i] = new JButton(str[i]);
            gb.setConstraints(btn[i], c);
            add(btn[i]);    
        }
        
        c.gridy = 4 ;
        for(int i =12;i<16;i++){
            btn[i] = new JButton(str[i]);
            gb.setConstraints(btn[i], c);
            add(btn[i]);    
        }
        
        
        
        /***
         * ActionEvent
         * getActionCo返回与命令相关的字符串
         * 添加事件
         * */
        
        
        for(int i= 0;i<btn.length;i++){
            btn[i].addActionListener(this);
        }
        
        setVisible(true);
    }
    
    
    
    @Override
    public void actionPerformed(ActionEvent e) {
        //获取事件源
        
        Object temp = e.getSource();
        //789
        for(int i = 0 ;i<3;i++){
            if(temp == btn[i]){
            
                tf.setText(tf.getText()+btn[i].getActionCommand());
            }
        }
        
        
        //456
        for(int i = 4 ;i<7;i++){
            if(temp == btn[i]){
            
                tf.setText(tf.getText()+btn[i].getActionCommand());
            }
        }
        
        //123
                for(int i = 8 ;i<11;i++){
                    if(temp == btn[i]){
            
                        tf.setText(tf.getText()+btn[i].getActionCommand());
                    }
                }
                
                // . 0 需要先判读是不是存在小数点假如存在小数点则不处理
                /**
                 * api 中看到方法
                 *  boolean contains(CharSequence s) 
                   *    当且仅当此字符串包含指定的 char 值序列时，返回 true。 
                   *先转换成char数组然后 判断是否存在
                 * */
                
                if(!iscontains(tf.getText(),‘.‘)){
                        if(temp.equals(btn[12])){
                            
                            tf.setText(tf.getText()+btn[12].getActionCommand());
                        }
                }
                if(temp.equals(btn[13])){
                    tf.setText(tf.getText()+btn[13].getActionCommand());
                }
                
                
                //CE
                if(temp.equals(btn[16])){
                    tf.setText("");
                }
                
                
                
                
                //运算
                //3 7 11 15 /*-+
            if(temp == btn[3]){
                //获取数字进行计算
                num1 = Double.parseDouble(tf.getText());
                opt = "/";
                tf.setText("");
                }
            
                
            if(temp == btn[7]){
                
                num1 = Double.parseDouble(tf.getText());
                opt = "*";
                tf.setText("");
            }        
                
            
            if(temp == btn[11]){
                num1 = Double.parseDouble(tf.getText());
                opt = "-";
                tf.setText("");
            }    
            
            
            if(temp == btn[15]){
                
                num1 = Double.parseDouble(tf.getText());
                opt = "+";
                tf.setText("");
            }
            
            if(temp == btn[14]){
                num2 = Double.parseDouble(tf.getText());
                
                switch(opt){
                case "+":result = num1+num2; break;
                case "-" :result = num1-num2; break;
                case "*" :result = num1*num2; break;
                case "/" :result = num1/num2;break;
                default:tf.setText("运算符出错");break;
                }
                tf.setText(result+"");
                
            }
            
            
    }
    /**
     * 判断字符串是否包含指定字符方法
     * */
    boolean iscontains(String str,char ch){
        
        //拆分字符串
        char c[] = str.toCharArray();
        for(int i =0;i<c.length;i++){
            if(c[i] == ‘.‘){
                return true;
            }
            
        }
        return false;
    } 
    
    
    public static void main(String[] args) {
        cal c = new cal();
        c.launch();

    }

    

}