package test1;
/**
 * 
 */
import java.awt.Button;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;

public class Calculator extends JFrame implements ActionListener{
	//定义成员变量
	JLabel show = new JLabel();
	JLabel rsult = new JLabel("0");
	String s="";//存放数字
	String operator="";//存放运算符
	double resultNum=0;//计算结果
	String ShowString="";
	
	
	public  Calculator() {

		
		JPanel top = new JPanel();
		
		top.setLayout(null);//无布局
		top.setBounds(16,10,260,100);//x周为16,y轴为10,宽为260，高为100
		top.setBackground(Color.white);//top的背景颜色
		//添加lable到面板
		show.setBounds(0,0,260,40);//x轴，y轴，宽，高
		show.setHorizontalAlignment(SwingConstants.RIGHT);//文本内容右对齐
		
		rsult.setBounds(0,40,260,60);//x轴，y轴，宽，高
		rsult.setHorizontalAlignment(SwingConstants.RIGHT);//文本内容右对齐
		rsult.setFont(new Font("黑体",1,25));//字体，int风格，字号
		
		top.add(show);
		top.add(rsult);
		top.setBorder(BorderFactory.createLineBorder(Color.blue));
		//窗口下面的一个网格布局的JPanel
		JPanel jp =new JPanel();
		
		jp.setLayout(new GridLayout(5,4,2,2));
		jp.setBounds(16,120,260,240);
		
		
		String[] str= {"%","C","←","÷","7","8","9","×","4","5","6","-","1","2","3","+","±","0",".","="};
		for(int i=0;i<=19;i++) {
			Button but=new Button(str[i]);
			jp.add(but);
			but.addActionListener(this);
		}
			
		this.add(jp);
		this.add(top);
		this.setLayout(null);//不使用布局管理器
		this.setTitle("计算器");
		this.setLocation(400,200);//窗口出现的位置
		this.setSize(300,400);//计算器大小  宽265，高450
		this.setVisible(true);//窗体可见
		this.setResizable(false);//不改变窗体大小
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//关闭程序
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		new Calculator();
	
	
	}
	//---事件处理器
	@Override
	public void actionPerformed(ActionEvent e) {
		//把数字显示在rsult上
				String label=e.getActionCommand();
				if("0123456789.".indexOf(label)>=0) {
					s=s+label;
					rsult.setText(s);
				}else if("+-×÷".indexOf(label)>=0) {
					handleOperator(label);
				}else if(label=="=") {
					show.setText(ShowString+getNumberFromLabel()+"=");
					if(operator=="+") {
						resultNum=(resultNum+getNumberFromLabel());	
					}else if(operator=="-") {
						resultNum=(resultNum-getNumberFromLabel());	
					}else if(operator=="×") {
						resultNum=(resultNum*getNumberFromLabel());	
					}else if(operator=="÷") {
						resultNum=(resultNum/getNumberFromLabel());	
					}
					
					rsult.setText(String.valueOf(resultNum));
					s="";
				
				}else if(label=="C") {
				 s="";//存放数字
				 operator="";//存放运算符
				 resultNum=0;//计算结果
				 ShowString="";//显示第一显示框的内容
				 show.setText("");
				 rsult.setText("0");
			}
		}

			
			//处理运算符
			 void handleOperator(String label) {
				operator=label;
				resultNum=getNumberFromLabel();//获取第一个数字
				ShowString = resultNum+operator;
				show.setText(ShowString);
				s="";//清空第一个数字
			}
			 //将rsult显示框的字符串转化为可计算的double类型
			 double getNumberFromLabel() {
				  double result;
				  result=Double.valueOf(rsult.getText()).doubleValue();
				  return result;
			  }

	}