calculator.java

利用Swing组件设计一个计算器

//计算器实现加、减、乘、除
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Calculator extends JFrame implements ActionListener
{
    
    private JTextField m_textField=new JTextField(12);
    private JButton[]m_button={
        new JButton("1"),new JButton("2"),new JButton("3"),new JButton("4"),
        new JButton("5"),new JButton("6"),new JButton("7"),new JButton("8"),
        new JButton("9"),new JButton("0"),new JButton("+"),new JButton("-"),
        new JButton("*"),new JButton("/"),new JButton("."),new JButton("="),
        new JButton("C")};
    
   
    public Calculator() 
    {
        super("Calculator");
        Container container=getContentPane();
        container.setLayout(new FlowLayout(FlowLayout.CENTER));
        
        container.add(m_textField);
                
        container.add(m_button[16]);
        
        container.add(m_button[0]);
        container.add(m_button[1]);
        container.add(m_button[2]);
        container.add(m_button[10]);
        
        container.add(m_button[3]);
        container.add(m_button[4]);
        container.add(m_button[5]);
        container.add(m_button[11]);
        
        container.add(m_button[6]);
        container.add(m_button[7]);
        container.add(m_button[8]);
        container.add(m_button[12]);
        
        container.add(m_button[9]);
        container.add(m_button[14]);
        container.add(m_button[15]);
        container.add(m_button[13]);
        
        for(int i=0;i<=16;i++)
          m_button[i].addActionListener(this);
        
        setSize(200,200);
        setVisible(true);
    }
    
    int flag,flag2;
    double value1,value2,result;//定义两个运算数和结果
    public void actionPerformed(ActionEvent e) 
    {
       
        int i;
        for(i=0;i<10;i++)
        {
            if(e.getSource()==m_button[i])
            {
                if(flag2==1)      //若等号后再输数字，则清空
                    m_textField.setText("");
                flag2=0;
                String value=String.valueOf((i+1)%10);
                m_textField.setText(m_textField.getText()+value);
             }
        }
           
       if(e.getSource()==m_button[10])  //加
       {
          flag=1;
           value1=Double.parseDouble(m_textField.getText());//得到第一个计算数
           m_textField.setText("");                        //清空
          
       }
       else if(e.getSource()==m_button[11])  //减
       {
           flag=2;
           value1=Double.parseDouble(m_textField.getText());
           m_textField.setText("");
          
       }
       else if(e.getSource()==m_button[12])//乘
       {
           flag=3;
           value1=Double.parseDouble(m_textField.getText());
           m_textField.setText("");
          
      }
       else if(e.getSource()==m_button[13])    //除
      {
           flag=4;
           value1=Double.parseDouble(m_textField.getText());
           m_textField.setText("");
           
       }
       else if(e.getSource()==m_button[15])   //＝
       {
          value2=Double.parseDouble(m_textField.getText());  //得到另一个计算数
          flag2=1;
          if(flag==1) result=value1+value2;                   //运算
          else if(flag==2) result=value1-value2;
          else if(flag==3) result=value1*value2;
          else if(flag==4){
              if(value2!=0) result=value1/value2;
              else result=0;
         }
          String r=String.valueOf(result);
          m_textField.setText(r);
       }
         else  if(e.getSource()==m_button[14])   //添加小数点
         {
            int flag1=1;
            String r=m_textField.getText();//判断文本框内的字符串中是否已经含有“.”若有，则按“.”键无效，若无，则输出“.”
            for(int j=0;j<r.length();j++)
            {
                if(r.charAt(j)==".".charAt(0))
                    flag1=0;
            }
            if(flag1==1)
                   m_textField.setText(m_textField.getText()+ ".");
         }
         else if(e.getSource()==m_button[16])    //复位，清空
                  m_textField.setText("");
       
    }
    
     public static void main(String args[])
    {
        Calculator app=new Calculator();
        app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    
}