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JAVA---编写计算器

时间:2017-09-15 20:20:51      阅读:360      评论:0      收藏:0      [点我收藏+]

标签:action   add   ace   private   数字   extends   pen   close   监听器   

import javax.swing.*;

import javax.swing.JTextField;

import java.awt.*;

import java.awt.event.*;

import java.lang.*;

import java.awt.Color;

public class Jisuanqi extends JFrame implements ActionListener{

private JPanel p1=new JPanel();//创建面板

private JPanel p2=new JPanel();

private JTextField t1;//文本框1用来显示输入信息

private JTextField t2;//文本框2用来显示结果信息

private JLabel label;//标签信息

StringBuffer str;//显示屏显示的字符

double x,y;//x和y都是运算数

int z;      //z表示单击那个运算符,0表示+,1表示-,2表示*,3表示 /

private JButton b[]=new JButton[12];//创建一个有12个按钮的数组

private JButton b1,b2,b3,b4,b5,b6,b7,b8;//算术功能按钮

 

public Jisuanji(){

              super("简易计算器"); //窗口名称

              Container c=getContentPane();//创建内容面板对象

              t1=new JTextField(30);

              t1.setEditable(false);//只能显示,不能编辑

               t2=new JTextField(30);

              t2.setEditable(false);//只能显示,不能编辑

               label=new Label("欢迎使用小计算器");

               label.setForeground(Color.blue);

              //创建一个空字符串缓冲区

              str=new StringBuffer();//添加标签到面板

              p2.add(label);//添加标签到面板

              p2.add(t2);//添加文本框到面板

              p2.add(t1);//添加文本框到面板

              p2.setLayout(new GridLayout(4,1));//把面板布局为4行1列

              for(int i=0;i<10;i++){   //分别为数组中0~9号按钮设置标签,并注册监听器

                       String s=""+i;

                       b[i]=new JButton(s);

                        b[i].addActionListener(this);

                              }

                 //实例化各个按钮

               b[10]=new JButton("-/+");b[11]=new JButton(".");

                b1=new JButton("/");  b2=new JButton("Back");

                 b3=new JButton("*");  b4=new JButton("C");

                 b5=new JButton("+"); b6=new JButton("Sqrt");

                 b7=new JButton("-"); b8=new JButton("=");

                 //设置按钮前颜色

            for(int i=0;i<12;i++){

                   b[i].setForegound(Color.blue);

                              }

             b1.setForeground(Color.red);  b3.setForeground(Color.red);

    b5.setForeground(Color.red);  b7.setForeground(Color.red);
    b2.setForeground(Color.blue);  b4.setForeground(Color.blue);
    b6.setForeground(Color.red);   b8.setForeground(Color.blue);

                 //添加到面板

               p1.add(b[7]);p1.add(b[8]);p1.add(b[9]);p1.add(b1);p1.add(b2);

               p1.add(b[4]);p1.add(b[5]);p1.add(b[6]);p1.add(b3);p1.add(b4);

                p1.add(b[1]);p1.add(b[2]);p1.add(b[3]);p1.add(b5);p1.add(b6);

                p1.add(b[0]);p1.add(b[10]);p1.add(b[11]);p1.add(b7);p1.add(b8);

                 p1.setLayout(new GridLayout(4,5,5,5));

              //注册监听器

            b[10]addActionListener(this);b[11].addActionListener(this);

            b1.addActionListener(this);b2.addActionListener(this);

            b3.addActionListener(this);b4.addActionListener(this);

            b5.addActionListener(this);b6.addActionListener(this);

             b7.addActionListener(this);b8.addActionListener(this);

            //将面板添加到内容面板

             c.add(p2);

             c.add(p1);

             c.setLayout(new FlowLayout());//设置顺序布局

              setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置窗口关闭动作

              setVisible(true);//设置为可见

               setResizable(false);//禁止调整框架大小

                setSize(400,300);//设置窗口大小

                }

                //主方法实现创建一个窗口

              public static void main(String[]args){

                       Jisuanqi f=new Jisuanqi();

                                       }

            //按钮的事件处理

            public void actionPerformed(ActionEvent e){

                             try{

                                      if(e.getSource()==b4){    //选择C清零

                                                   t1.setText("0");//把文本框清零

                                                   t1.setHorizontalAlignment(JTextField.LEFT);//文本左对齐

                                                    str.setLength(0);//清空字符串缓冲区

                                                      }

                                          else if(e.getSource()==b[10]){              //单击“+/-”,选择输入的数是正数还是负数

                                           x=Double.parseDouble(t1.getText().trim());//trim函数的作用是去掉字符串中的空格                       t1.setText(""+(-x));

                                            t1.setHorizontalAlignment(JTextField.LEFT);

                                                 }

                                              else if(e.getSource()==b5){          //点击加号按钮获取x和z的值,并清空y值

                                           x=Double.parseDouble(t1.getText().trim());

                                            str.setLength(0);

                                            y=0d;

                                            z=0;

                                           }

                           else if(e.getSource()==b7){              //单击减号获得x和z的值,并清空y值

                                         x=Double.parseDouble(t1.getText().trim());

                                         str.setLength(0);

                                          y=0d;

                                          z=1;

                                                }

                             else if(e.getSource()==b3){             //单击乘号按钮获得x和z的值,并清空有的值

                                      x=Double.parseDouble(t1.getText().trim());

                                       str.length(0);

                                       y=0d;

                                        z=2;

                                              }

                                       else if(e.getSource()==b1){            //单击除号按钮获得x的值和z值的

                                             x=Double.parseDouble(t1.getText().trim());

                                             str.setLength(0);

                                              y=0d;

                                              z=3;

                                                     }

                                       else if(e.getSource()==b8{           //单击等号按钮输出计算结果

                                             str.length(0);

                                              seitch(z){

                                                case 0: t1.setText(""+(x+y)); t1.setHorizontalAlignment(JTextField.LEFT);break;

                                                case 1: t1.setText(""+(x-y)); t1.setHorizontalAlignment(JTextField.LEFT);break;

                                                case 2:  t1.setText(""+(x*y)); t1.setHorizontalAlignment(JTextField.LEFT);break;

                                                 case 3: t1.setText(""+(x/y));  t1.setHorizontalAlignment(JTextField.LEFT);break;

                                                     }

                                             }

                                      else if(e.getSource()==b[11]) {             //单击"."按钮输入小数

                                            if(t1.getText().trim().indexOf(‘.‘)!=-1){               //判断字符串是否已经包含了小数点

                                                 }

                                            else{    //如果没有小数点

                                                   if(t1.getText().trim().equals("0"){      //如果初始显示为0

                                                                                   t1.setText(str.append(e.getActionCommand()).toString());

                                                                                   t1.setHorizontalAlignment(JTextField.LEFT);

                                                  }else if(t1.geText().trim().equals("")){             //如果初始显示为空则不做任何操作

                                                                   }

                                                       else{

                                                                t1.setText(str.append(e.getActionCommand()).toString());

                                                                t1.setHorizontalAlignment(JTextField.LEFT);

                                                                }

                                                           }

                                                        y=0d;

                                             }

                                            else if(e.getSource()==b6){               //求平方根

                                                             x=Double.parseDouble(t1.getText().trim());

                                                            if(x<0){

                                                                     t1.setText("数字格式异常");

                                                                     t1.setHorizontalAlignment(JTextField.LEFT);

                                                                           }

                                                                else{

                                                                             t1.setText(""+Math.sqrt(x));

                                                                             t1.setHorizontalAlignment(JTextField.LEFT);

                                                                               }

                                                                       str.setLength(0);

                                                                          y=0d;

                                                                          }

                                                               else{

                                                                          if(e.getSource()==b[0]){              //如果选择是“0”这个数字键

                                                                                           if(t1.getText().trim().equals("0");{  

                                                                                                       }//如果显示屏显示的是0,则不做操作

                                                                                                else

                                                                                                        t1.setText(str.append(e.getActionCommand()).toString());

                                                                                                         t1.setHorizontalAlignment(JTextField.LEFT);

                                                                                                          y=Double.parseDouble(t1.getText().trim());

                                                                                                  }

                                                                         else if(e.getSource()==b2){              //返回的是back键

                                                                                        if(!t1.getText().trim().equals("0")){      //如果显示屏显示的不是0

                                                                                              

        if(str.length()!=1
        
          t1.setText(str.delete(str.length()-1,str.length()).toString());//可能抛出字符串越界异常 
          t1.setHorizontalAlignment(JTextField.RIGHT);
        }
        else 
        
          t1.setText("0"); t1.setHorizontalAlignment(JTextField.RIGHT);
          str.setLength(0); 
        
      
      y=Double.parseDouble(t1.getText().trim()); 
      }
      else 
        {
        t1.setText(str.append(e.getActionCommand()).toString()); 
        t1.setHorizontalAlignment(JTextField.RIGHT);
        y=Double.parseDouble(t1.getText().trim());
        }
      }
    }
    catch(NumberFormatException e1){ t1.setText("数字格式异常");
    t1.setHorizontalAlignment(JTextField.RIGHT); } 
  
    catch(StringIndexOutOfBoundsException e1){t1.setText("字符串索引越界");
    t1.setHorizontalAlignment(JTextField.RIGHT);} 
  }
}

 

                                                                                                            

                                          

                       

              

 

                                                                            

                                                                

                                                     

        

                         

                  

 

JAVA---编写计算器

标签:action   add   ace   private   数字   extends   pen   close   监听器   

原文地址:http://www.cnblogs.com/zhouzetian/p/7527832.html

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