calculatordemonstration.java

这是一个用java实现的计算器

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
 class Calculator extends JFrame   // 主体功能实现类
{ Container container;

  String[] str1={"MC","7","8","9","/","sqrt","MR","4","5","6","*","%","MS","1","2","3","-","1/x","M+","0","+/-",".","+","="};
  String[] str2={"Backspace","CE","C"};        //使用字符串数组来实现程序的优化
  
  JButton[] grd =new JButton[str1.length];   //JButton对象数组来管理所有键
  JButton[] BCC =new JButton[str2.length];
   
  JPanel pane1,pane2,pane12,pane123;
   
  JTextField Msig,displayField;
  String lastCommand, store="0";  //lastCommand存储上次的操作符，store主要是用来存储M操作符的计算结果的
  static double result;  //存储控制符算出的结果
  boolean start,flag,lag;  //三个标志符



   Calculator()
     {   super("计算器");
         setSize(420,320);
         container=getContentPane();
         pane1 = new JPanel();  //下面24个键
         pane2 = new JPanel();  //中间4个键
         pane12 = new JPanel();  
         pane123 =new JPanel();
         
         Msig =new JTextField();  //M显示区域
         Msig.setHorizontalAlignment(JTextField.CENTER);  //中间对齐
         
         displayField =new JTextField();  //输入数字显示区
         displayField.setHorizontalAlignment(JTextField.RIGHT);  //右对齐
        displayField.setBackground(Color.white);   //底色为白色
        
         
         Msig.setEditable(false);   //使两个可编辑文本框不可通过鼠标和键盘编辑
         displayField.setEditable(false);
         
         pane1.setLayout(new GridLayout(4,6,5,5));  //为面板设置排版类型
         pane2.setLayout(new GridLayout(1,4,5,5));
         pane12.setLayout(new BorderLayout(5,5));
         pane123.setLayout(new BorderLayout(5,5));
        
         ActionListener insert = new InsertAction();   //三个事件监听类初始化
	 ActionListener commanda = new CommandaAction();
         ActionListener commandb = new CommandbAction();
         start=true;  //为标志符设初值
         flag=false;
         lag=false;
         result=0;   //result和lastcommand设初值
	 lastCommand = "=";
        
        for(int i=0;i<=str1.length-1;i++)  //为pane1面板添加JButton，通过循环实现
           { grd[i]=new JButton(str1[i]);   
             
             if((i%6)==0) 
                grd[i].setBackground(Color.green);  //M键涂成绿色
             if((((i-4)%6)==0)||(i==str1.length-1)) //加减乘除等于号涂色和注册事件监听类
                { grd[i].setBackground(Color.yellow);
                  grd[i].addActionListener(commanda);
                }
             else if((i-5)%6==0&&(i!=str1.length-1)) grd[i].addActionListener(commandb);  //sqrt，％，1/x注册
             else       grd[i].addActionListener(insert);  //其他键注册事件监听
             pane1.add(grd[i]);  //添加JButton
            }
       
       
         pane2.add(Msig);  
         for(int i=0;i<=str2.length-1;i++)  //为pane2面板添加JButton和注册事件监听类
           { BCC[i]=new JButton(str2[i]);
             pane2.add(BCC[i]);
             BCC[i].setBackground(Color.blue);
             BCC[i].addActionListener(new InsertAction());
            }
        pane12.add(pane2,BorderLayout.NORTH);  //按BorderLayout来添加pane1 ,2到pane12
        pane12.add(pane1,BorderLayout.CENTER);
        pane123.add(displayField,BorderLayout.NORTH);
        pane123.add(pane12,BorderLayout.CENTER);
        container.add(pane123);
       
        setVisible(true);
      
     }
    class InsertAction implements ActionListener {   //insetAction事件监听类
                  
		public void actionPerformed(ActionEvent event) {
                        
			String input=event.getActionCommand();  //设置input为按下的键的text区字符串
                        if(input.equals("+/-"))
				displayField.setText("-"+displayField.getText());  //显示字符串
			if (start) {
				displayField.setText("");
				start=false;
                                    }    //如果start＝true，不保留原来的结果，重新开始计算，setText为空
	
			if(!input.equals("+/-")) {
				if(input.equals("Backspace")) {  //如果按键是Backspace
					String str=displayField.getText();
					if(str.length()>0)
			 			displayField.setText(str.substring(0,str.length()-1));
				         }else if(input.equals("CE")||input.equals("C"))	{  //如果按键是CE或C
					         displayField.setText("0");
					         flag=true;
                                                 lag=true;
                                                 result=0;  
                                                 lastCommand = "=";
                                      
				
                                         }else if(input.equals("MS")){  //如果是MS
                                               store=displayField.getText();
                                               Msig.setText("M");
                                          
                                         }else if(input.equals("MR")){  //如果是MR
                                          
                                            displayField.setText(store);
                                         }else if(input.equals("MC")){   //如果是MC
                                               store="0";
                                               Msig.setText("");
                                         }else if(input.equals("M+")){   //如果是M＋
                                         if(input!=null)  { double y=Double.parseDouble(displayField.getText())+Double.parseDouble(store);
                                                            Double Y=new Double(y);
                                                            store=Y.toString();
                                                           }   //如果有输入，将输入数和存储数相加存储
                                       
                                              else  { double y=Double.parseDouble(store)*2;
                                                      Double Y=new Double(y);
                                                     store=Y.toString();}
                                                     }  //如果没有输入，将存储数的2倍存储


                                  else {  if(lag)  { displayField.setText(input); lag=false;
                                                   }   //如果文本框上的数是0，只输出输入的那个数字，去掉0
                                           else 
                                            displayField.setText(displayField.getText()+input);
                                       }
                   }
		}
	}


    class CommandaAction implements ActionListener {  //CommandaAction类

		      public void actionPerformed(ActionEvent evt) {
			            String command1=evt.getActionCommand();
			          if(start) {
				              lastCommand=command1;
                               
                                
			              }else {
				               calculate(Double.parseDouble(displayField.getText()));  //先计算，后存command1
				               lastCommand=command1;
				               start=true;
                                               displayField.setText(""+ result);
			}
		}
	}
           class CommandbAction implements ActionListener {  //CommandbAction类

		public void actionPerformed(ActionEvent ev) {
			String command2=ev.getActionCommand();
	        if(!flag){	lastCommand=command2;    //先存储command2后计算
		                calculate(result);
                             displayField.setText(""+ result);
			}
                 else {	   //处理如果一开始就输入数在对其求方根或倒数的情况
                        calculate(Double.parseDouble(displayField.getText()));
                        lastCommand=command2;
                        calculate(result);
                        displayField.setText(""+ result);
                        flag=false;
                       }
		}
		
	}








	public void calculate(double x) {    //计算部分，通过lastCommand来实现
		if (lastCommand.equals("+")) result+= x;    
		else if (lastCommand.equals("-")) result-=x;
		else if (lastCommand.equals("*")) result*=x;   
		else if (lastCommand.equals("/")) result/=x;
		else if (lastCommand.equals("=")) result=x;
                else if (lastCommand.equals("sqrt")) result=Math.sqrt(x);
		else if (lastCommand.equals("%")) result=x/100;
                else if (lastCommand.equals("1/x")) result=1/x;
		
  
		
	}
     
}  
public class CalculatorDemonstration{    //显示函数
  public static void main(String[] args) {
             try{
                 UIManager.setLookAndFeel(
                   UIManager.getCrossPlatformLookAndFeelClassName());
                }catch(Exception e){}
             Calculator test  = new Calculator();
       
             test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
    }
}