calculator.java

用纯java编写的一个gui界面计算器

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class Calculator extends JFrame implements ActionListener{
	
	private Container c = getContentPane();
	public Calculator(){
		
		JPanel head = getHeaderPanel();
		c.add(head,BorderLayout.NORTH);
		JPanel option = getOptionPanel();
		c.add(option,BorderLayout.CENTER);
		
		init(true);
		
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setTitle("计算器");
		setSize(270,135);
		setResizable(false);
		setVisible(true); 
	}
	
	private JButton getButton(String text) {   
		JButton btnTemp = new JButton(text); 
		btnTemp.addActionListener(this);
		return btnTemp; 
	}
	
	private JTextField txtAccountResult;
	private JPanel getHeaderPanel(){
		
		JPanel panel = new JPanel();
		
		txtAccountResult = new JTextField(42);
        txtAccountResult.setEditable(false);
		txtAccountResult.setBorder(BorderFactory.createLoweredBevelBorder());
		txtAccountResult.setHorizontalAlignment(JTextField.RIGHT);
		txtAccountResult.setCursor(new Cursor(Cursor.TEXT_CURSOR));
		panel.add(txtAccountResult);
		
		return panel;
	}
	
	private JPanel getOptionPanel(){
	 	
		JPanel panel = new JPanel();
	 	panel.setLayout(new GridLayout(3,6,5,5));
	 	
	 	panel.add(getButton("7"));
		panel.add(getButton("8"));
		panel.add(getButton("9"));
		panel.add(getButton("0"));
		panel.add(getButton("+"));
		panel.add(getButton("-"));
		panel.add(getButton("4"));
		panel.add(getButton("5"));
		panel.add(getButton("6"));
		panel.add(getButton("."));
		panel.add(getButton("*"));
		panel.add(getButton("/"));
		panel.add(getButton("1"));
		panel.add(getButton("2"));
		panel.add(getButton("3"));
		panel.add(getButton("="));
        panel.add(getButton("M"));
        panel.add(getButton("C"));
		
		return panel;
	}
	
	private char sign;              //运算符号
    private double result;          //计算结果
    private double textTempValue;   //临时结果
    private boolean state;          //是否是第一次
    private String textValue;       //记录文本框的值
    private boolean start;          //是否刚刚按了"="
    
    private char msign;             //处于激活状态的符号
    private double mresult;         //处于激活状态的结果
    private boolean activeM;        //"M"键是否处于激活状态
	public void actionPerformed(ActionEvent e){
		
		String numberGroup = "0123456789";
		String signGroup   = "+-*/=";
		
		String input = e.getActionCommand();
		
		if(numberGroup.indexOf(input) != -1){
			
			if(start){
			    init(true);
			}
			if(textValue.equals("0")){
				textValue = "";
			}
			textValue += input;
			txtAccountResult.setText(textValue);
			
		}else if(signGroup.indexOf(input) != -1){
            try{
                textTempValue = Double.parseDouble(textValue);
            }catch(NumberFormatException ex){}
            if(state){
                result = textTempValue;
                state = false;
            }else{
                getValue(sign,textTempValue);
            }
            if(!input.equals("="))
                sign = signGroup.charAt(signGroup.indexOf(input));
            else
                start = true;
            textValue = "";
            txtAccountResult.setText(String.valueOf(result));
			
		}else if(input.equals("M")){
            if(activeM){
                try{
                    textTempValue = Double.parseDouble(textValue);
                }catch(NumberFormatException ex){}
                getValue(sign,textTempValue);
                getValue(msign,mresult);
                txtAccountResult.setText(String.valueOf(result));
                textValue = String.valueOf(result);
                msign   = ' ';
                mresult = 0.0;
                activeM = false;
                state = true;
		    }else{
		        msign   = sign;
			    mresult = result;
                init(false);
                txtAccountResult.setText(String.valueOf(mresult));
                activeM = true;
		    }
			
		}else if(input.equals("C")){
            init(true);
        }else if(input.equals(".")){
            if(textValue.indexOf(".") == -1){
                textValue += input;
                txtAccountResult.setText(textValue);
            }
        }
	}
	
	private void init(boolean isInit){
	    start = false;
        sign = ' ';
        result = 0.0;
        textTempValue = 0.0;
        state = true;
        textValue = "0";
        activeM = false;
        txtAccountResult.setText(textValue); 
        if(isInit){
            msign = ' ';
            mresult = 0.0;
        }
	}
	
	private void getValue(char sign,double temp){
		switch (sign){   
            case '+':result += temp;break;
            case '-':result -= temp;break;
            case '*':result *= temp;break;
            case '/':result /= temp;break;
		}
	}
	
	private static String windows =
			"com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
	public static void main(String[] args){
		try{
			UIManager.setLookAndFeel(windows);
		}catch(Exception e){
			e.printStackTrace();
		}
		new Calculator();
	}
}