calculator.java

此文件名叫暑期

import javax.swing.*;

import java.awt.*;
import java.awt.event.*;

public class Calculator {
	public static void main(String[] s){
		CalculatorFrame frame = new CalculatorFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
	}

}

class CalculatorFrame extends JFrame{
	public CalculatorFrame(){
		setTitle("计算器");
		CalculatorPanel panel = new CalculatorPanel();
		add(panel);
		pack();
	}
}
class CalculatorPanel extends JPanel{
	private JButton display;
	private JPanel panel;
	private double result;
	private String lastCommand;
	private boolean start;
	
	
	public CalculatorPanel(){
		setLayout(new BorderLayout());
		
		result = 0;
		lastCommand = "=";
		start = true;
		
		display = new JButton("0");
		display.setEnabled(false);
		add(display,BorderLayout.NORTH);
		
		ActionListener insert = new InsertAction();
		ActionListener command = new CommandAction();
		
		
		panel = new JPanel();
		panel.setLayout(new GridLayout(4,4));
		
		
		addButton("7",insert);
		addButton("8",insert);
		addButton("9",insert);
		addButton("/",command);
		
		addButton("4",insert);
		addButton("5",insert);
		addButton("6",insert);
		addButton("*",command);
		
		
		addButton("1",insert);
		addButton("2",insert);
		addButton("3",insert);
		addButton("-",command);
		
		addButton("0",insert);
		addButton(".",insert);
		addButton("=",command);
		addButton("+",command);
		
		add(panel,BorderLayout.CENTER);
		
			}
	
	private void addButton(String label,ActionListener listener){
		JButton button = new JButton(label);
		button.addActionListener(listener);
		panel.add(button);
	}
	private class InsertAction implements ActionListener{
		public void actionPerformed(ActionEvent event){
			String input =event.getActionCommand();
			if(start){
				display.setText("");
				start= false;
			}
			display.setText(display.getText()+input);
		}
	}
	private class CommandAction implements ActionListener{
		public void actionPerformed(ActionEvent event){
			String command = event.getActionCommand();
			if(start){
				if(command.equals("-")){
				    display.setText(command);
				    start =false;
			    }
			    else 
				lastCommand = command;
			}else
			{
				calculate(Double.parseDouble(display.getText()));
				lastCommand = command;
				start = true;
			}
		}

		
	}
	public void calculate(double x){
		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;
		display.setText(""+result);
	}
	
	
}