简易计算器

package com.mine;

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class Calc extends JFrame {
	Panel pan1 = new Panel();
	Panel pan2 = new Panel();
	Panel pan3 = new Panel();
	JButton[] btn = new JButton[17];
	JTextField txt;
	static String sign;  //用来存储计算符
	static double temp ; //存储计算结果
	String[] str = { "7", "8", "9", "+", "4", "5", "6", "-", "1", "2", "3",
			"*", "0", ".", "=", "/", "清空" }; //String数组用来存储按键信息

	public Calc(String name) {
		super(name);

		pan1.setLayout(new BorderLayout());

		pan2.setLayout(new GridLayout(4, 4));

		pan3.setLayout(new BorderLayout());
		 txt = new JTextField();
		this.setVisible(true);
		this.setSize(175, 220);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setLocationRelativeTo(null);
		this.setResizable(false);
		for (int i = 0; i < btn.length; i++) {
			btn[i] = new JButton(str[i]);
		}
		for (int j = 0; j < btn.length; j++) {
			pan2.add(btn[j]);
		}
		for (int i = 0; i <btn.length; i++) {
			btn[i].addActionListener(new buttonlistener());//添加监听器
		}
		pan1.add(txt, "North");
		pan3.add(btn[16]);
		this.add(pan1, "North");
		this.add(pan2, "Center");
		this.add(pan3, "South");
	}
	class buttonlistener implements ActionListener{  //按钮监听事件,根据按键给不同德结果

		@Override
		public void actionPerformed(ActionEvent e) {
			JButton btn = (JButton) e.getSource(); //获得数据源
			if (btn.getText().equals("=")) {
				Numeration();
				txt.setText(String.valueOf(temp));
				sign = "";
				} else if (btn.getText().equals("+")) {
					Numeration();
					txt.setText("");
					sign = "+";
				} else if (btn.getText().equals("-")) {
					Numeration();
					txt.setText("");
					sign = "-";
				} else if (btn.getText().equals("/")) {
					Numeration();
					txt.setText("");
					sign = "/";
				} else if (btn.getText().equals("*")) {
					Numeration();
					txt.setText("");
					sign = "*";
				} else {
				txt.setText(txt.getText() + btn.getText()); //文本框显示数字
				if (btn.getText() == "清空"){//点击清空按钮,则把所有信息重新赋为空
					txt.setText("");
					sign="";
					temp=0;
				}
				}
				}
				public void Numeration() {//编写具体计算方法
				if (sign == "+"){
				temp += Double.parseDouble(txt.getText());
				}else if (sign == "-"){
				temp -= Double.parseDouble(txt.getText());
				}else if (sign == "*"){
				temp *= Double.parseDouble(txt.getText());
				}else if (sign == "/"){
				temp /= Double.parseDouble(txt.getText());
				}else{		//如果按=,则
				temp = Double.parseDouble(txt.getText());
					}
		}
		
	}
public static void main(String[] args) {
		JFrame.setDefaultLookAndFeelDecorated(true);
		Calc c = new Calc("计算器");
	}
}