Java实现常规的计算器（网格布局）-蒲公英云

Java实现常规的计算器（网格布局）

计算器的布局比较整齐，利用网格布局排列计算器按钮是一种比较理想的方式，实现的java程序如下：

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
/**
 * 
 * @author IWong
 *
 */
public class Calculator {
    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
             CalculatorFrame frame = new CalculatorFrame();
             frame.setTitle("计算器");
             frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
             frame.setVisible(true);
          });
    }
}
class CalculatorFrame extends JFrame{
    public CalculatorFrame() {
        add(new CalculatorPanel());
        pack();
    }
}
class CalculatorPanel extends JPanel{
    private JPanel panel;
    private JTextField display;
    private double result;
    private String lastcommand;
    private boolean start=true;
    public CalculatorPanel() {
        setLayout(new BorderLayout());
        display=new JTextField();
        display.setHorizontalAlignment(JTextField.RIGHT);
        result=0;
        display.setText(""+result);
        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 s, ActionListener listener) {
        JButton button=new JButton(s);
        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(command.equals("=")){            
                if(lastcommand.equals("+")) result+=Double.parseDouble(display.getText());            
                if(lastcommand.equals("-")) result-=Double.parseDouble(display.getText());            
                if(lastcommand.equals("*")) result*=Double.parseDouble(display.getText());            
                if(lastcommand.equals("/")) result/=Double.parseDouble(display.getText());
                display.setText(""+result);
                start=true;
            }else{
                result=Double.parseDouble(display.getText());            
                lastcommand=command;
                start=true;
            }
        }
    }
}