diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000000000000000000000000000000000000..ee5839968a2bf86c93283efc09d40fd050b7cfa2
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,127 @@
+                     木兰宽松许可证, 第2版
+
+   木兰宽松许可证， 第2版 
+   2020年1月 http://license.coscl.org.cn/MulanPSL2
+
+
+   您对“软件”的复制、使用、修改及分发受木兰宽松许可证，第2版（“本许可证”）的如下条款的约束：
+
+   0. 定义
+
+      “软件”是指由“贡献”构成的许可在“本许可证”下的程序和相关文档的集合。
+
+      “贡献”是指由任一“贡献者”许可在“本许可证”下的受版权法保护的作品。
+
+      “贡献者”是指将受版权法保护的作品许可在“本许可证”下的自然人或“法人实体”。
+
+      “法人实体”是指提交贡献的机构及其“关联实体”。
+
+      “关联实体”是指，对“本许可证”下的行为方而言，控制、受控制或与其共同受控制的机构，此处的控制是指有受控方或共同受控方至少50%直接或间接的投票权、资金或其他有价证券。
+
+   1. 授予版权许可
+
+      每个“贡献者”根据“本许可证”授予您永久性的、全球性的、免费的、非独占的、不可撤销的版权许可，您可以复制、使用、修改、分发其“贡献”，不论修改与否。
+
+   2. 授予专利许可
+
+      每个“贡献者”根据“本许可证”授予您永久性的、全球性的、免费的、非独占的、不可撤销的（根据本条规定撤销除外）专利许可，供您制造、委托制造、使用、许诺销售、销售、进口其“贡献”或以其他方式转移其“贡献”。前述专利许可仅限于“贡献者”现在或将来拥有或控制的其“贡献”本身或其“贡献”与许可“贡献”时的“软件”结合而将必然会侵犯的专利权利要求，不包括对“贡献”的修改或包含“贡献”的其他结合。如果您或您的“关联实体”直接或间接地，就“软件”或其中的“贡献”对任何人发起专利侵权诉讼（包括反诉或交叉诉讼）或其他专利维权行动，指控其侵犯专利权，则“本许可证”授予您对“软件”的专利许可自您提起诉讼或发起维权行动之日终止。
+
+   3. 无商标许可
+
+      “本许可证”不提供对“贡献者”的商品名称、商标、服务标志或产品名称的商标许可，但您为满足第4条规定的声明义务而必须使用除外。
+
+   4. 分发限制
+
+      您可以在任何媒介中将“软件”以源程序形式或可执行形式重新分发，不论修改与否，但您必须向接收者提供“本许可证”的副本，并保留“软件”中的版权、商标、专利及免责声明。
+
+   5. 免责声明与责任限制
+
+      “软件”及其中的“贡献”在提供时不带任何明示或默示的担保。在任何情况下，“贡献者”或版权所有者不对任何人因使用“软件”或其中的“贡献”而引发的任何直接或间接损失承担责任，不论因何种原因导致或者基于何种法律理论，即使其曾被建议有此种损失的可能性。 
+
+   6. 语言
+      “本许可证”以中英文双语表述，中英文版本具有同等法律效力。如果中英文版本存在任何冲突不一致，以中文版为准。
+
+   条款结束 
+
+   如何将木兰宽松许可证，第2版，应用到您的软件
+   
+   如果您希望将木兰宽松许可证，第2版，应用到您的新软件，为了方便接收者查阅，建议您完成如下三步：
+
+      1， 请您补充如下声明中的空白，包括软件名、软件的首次发表年份以及您作为版权人的名字；
+
+      2， 请您在软件包的一级目录下创建以“LICENSE”为名的文件，将整个许可证文本放入该文件中；
+
+      3， 请将如下声明文本放入每个源文件的头部注释中。
+
+   Copyright (c) [Year] [name of copyright holder]
+   [Software Name] is licensed under Mulan PSL v2.
+   You can use this software according to the terms and conditions of the Mulan PSL v2. 
+   You may obtain a copy of Mulan PSL v2 at:
+            http://license.coscl.org.cn/MulanPSL2 
+   THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.  
+   See the Mulan PSL v2 for more details.  
+
+
+                     Mulan Permissive Software License，Version 2
+
+   Mulan Permissive Software License，Version 2 (Mulan PSL v2)
+   January 2020 http://license.coscl.org.cn/MulanPSL2
+
+   Your reproduction, use, modification and distribution of the Software shall be subject to Mulan PSL v2 (this License) with the following terms and conditions: 
+   
+   0. Definition
+   
+      Software means the program and related documents which are licensed under this License and comprise all Contribution(s). 
+   
+      Contribution means the copyrightable work licensed by a particular Contributor under this License.
+   
+      Contributor means the Individual or Legal Entity who licenses its copyrightable work under this License.
+   
+      Legal Entity means the entity making a Contribution and all its Affiliates.
+   
+      Affiliates means entities that control, are controlled by, or are under common control with the acting entity under this License, ‘control’ means direct or indirect ownership of at least fifty percent (50%) of the voting power, capital or other securities of controlled or commonly controlled entity.
+
+   1. Grant of Copyright License
+
+      Subject to the terms and conditions of this License, each Contributor hereby grants to you a perpetual, worldwide, royalty-free, non-exclusive, irrevocable copyright license to reproduce, use, modify, or distribute its Contribution, with modification or not.
+
+   2. Grant of Patent License 
+
+      Subject to the terms and conditions of this License, each Contributor hereby grants to you a perpetual, worldwide, royalty-free, non-exclusive, irrevocable (except for revocation under this Section) patent license to make, have made, use, offer for sale, sell, import or otherwise transfer its Contribution, where such patent license is only limited to the patent claims owned or controlled by such Contributor now or in future which will be necessarily infringed by its Contribution alone, or by combination of the Contribution with the Software to which the Contribution was contributed. The patent license shall not apply to any modification of the Contribution, and any other combination which includes the Contribution. If you or your Affiliates directly or indirectly institute patent litigation (including a cross claim or counterclaim in a litigation) or other patent enforcement activities against any individual or entity by alleging that the Software or any Contribution in it infringes patents, then any patent license granted to you under this License for the Software shall terminate as of the date such litigation or activity is filed or taken.
+
+   3. No Trademark License
+
+      No trademark license is granted to use the trade names, trademarks, service marks, or product names of Contributor, except as required to fulfill notice requirements in Section 4.
+
+   4. Distribution Restriction
+
+      You may distribute the Software in any medium with or without modification, whether in source or executable forms, provided that you provide recipients with a copy of this License and retain copyright, patent, trademark and disclaimer statements in the Software.
+
+   5. Disclaimer of Warranty and Limitation of Liability
+
+      THE SOFTWARE AND CONTRIBUTION IN IT ARE PROVIDED WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED. IN NO EVENT SHALL ANY CONTRIBUTOR OR COPYRIGHT HOLDER BE LIABLE TO YOU FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO ANY DIRECT, OR INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES ARISING FROM YOUR USE OR INABILITY TO USE THE SOFTWARE OR THE CONTRIBUTION IN IT, NO MATTER HOW IT’S CAUSED OR BASED ON WHICH LEGAL THEORY, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+   6. Language
+
+      THIS LICENSE IS WRITTEN IN BOTH CHINESE AND ENGLISH, AND THE CHINESE VERSION AND ENGLISH VERSION SHALL HAVE THE SAME LEGAL EFFECT. IN THE CASE OF DIVERGENCE BETWEEN THE CHINESE AND ENGLISH VERSIONS, THE CHINESE VERSION SHALL PREVAIL.
+
+   END OF THE TERMS AND CONDITIONS
+
+   How to Apply the Mulan Permissive Software License，Version 2 (Mulan PSL v2) to Your Software
+
+      To apply the Mulan PSL v2 to your work, for easy identification by recipients, you are suggested to complete following three steps:
+
+      i Fill in the blanks in following statement, including insert your software name, the year of the first publication of your software, and your name identified as the copyright owner; 
+
+      ii Create a file named “LICENSE” which contains the whole context of this License in the first directory of your software package;
+
+      iii Attach the statement to the appropriate annotated syntax at the beginning of each source file.
+
+
+   Copyright (c) [Year] [name of copyright holder]
+   [Software Name] is licensed under Mulan PSL v2.
+   You can use this software according to the terms and conditions of the Mulan PSL v2. 
+   You may obtain a copy of Mulan PSL v2 at:
+               http://license.coscl.org.cn/MulanPSL2 
+   THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.  
+   See the Mulan PSL v2 for more details.  
diff --git a/src/java2020spring/Calculator.java b/src/java2020spring/Calculator.java
new file mode 100644
index 0000000000000000000000000000000000000000..b36d67efc1df902592064819f612a18d3dbc8b59
--- /dev/null
+++ b/src/java2020spring/Calculator.java
@@ -0,0 +1,293 @@
+package java2020spring;
+import java.awt.*;
+import javax.swing.*;
+import javax.swing.border.EmptyBorder;
+import javax.swing.text.JTextComponent;
+
+import java.math.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.io.BufferedReader;
+import java.io.FileOutputStream;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.Writer;
+import java.io.IOException;
+import java.io.FileNotFoundException;
+
+public class Calculator extends JFrame implements ActionListener{
+	/*北面的控件*/
+	private JPanel jp_north=new JPanel();
+	private JTextField input_text=new JTextField();
+	private JButton B_Btn=new JButton("Backspace");
+	private JButton C_Btn=new JButton("Clear");
+	/*中间的控件*/
+	private JPanel jp_center=new JPanel();
+	private JButton btn[]=new JButton[24];
+	
+	//可变字符串，显示屏所显示的字符串
+	StringBuffer str;
+	
+	//定义两个操作数
+	double x,y;
+	//z表示单击了哪个运算符(0表示+，1表示-，2表示*，3表示/）
+	int z;
+	
+
+
+	//窗体初始化
+	public Calculator() {
+		setTitle("计算器");
+		setBounds(400,200,500,200);//X.Y,W,H窗口位置大小
+		setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
+		setResizable(false);
+		setLayout(new BorderLayout());
+		str=new StringBuffer();//创建一个空字符串缓冲区
+		
+	
+	
+	//窗体北面设置
+		input_text.setPreferredSize(new Dimension(300,30));//设置文本框的大小
+		input_text.setEditable(false);//文本框只能显示，不能编辑
+		input_text.setBackground(Color.pink);//文本框颜色
+		jp_north.add(input_text);
+		jp_north.add(B_Btn);
+		jp_north.add(C_Btn);
+		C_Btn.setForeground(Color.RED);//将清空按钮Clear标为红色字体，提醒防误触清空
+		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		add(jp_north,BorderLayout.NORTH);
+		 B_Btn.addActionListener(this);
+		 C_Btn.addActionListener(this);
+		 
+
+	//窗体下方按钮设置
+      this.jp_center.setLayout(new GridLayout(4,6));
+    //给按钮添加文字内容
+      for(int i=0;i<24;i++) {
+    	  String s=""+i;
+    	  btn[i]=new JButton(s);
+    	  btn[0]=new JButton("7");
+        	btn[1]=new JButton("8");
+        	btn[2]=new JButton("9") ;
+          btn[3]=new JButton("+") ;
+          btn[4]=new JButton("±") ;
+          btn[5]=new JButton("二进制");
+          btn[6]=new JButton("4");
+          btn[7]=new JButton("5");
+          btn[8]=new JButton("6");
+          btn[9]=new JButton("-");
+          btn[10]=new JButton("1/x");
+          btn[11]=new JButton("八进制");
+          btn[12]=new JButton("1");
+          btn[13]=new JButton("2");
+          btn[14]=new JButton("3");
+          btn[15]=new JButton("*");
+          btn[16]=new JButton("√");
+          btn[17]=new JButton("十进制");
+          btn[18]=new JButton("%");
+          btn[19]=new JButton("0");
+          btn[20]=new JButton(".");
+          btn[21]=new JButton("/");
+          btn[22]=new JButton("x^2");
+          btn[23]=new JButton("=");
+        btn[i].setFont(new Font("楷体",Font.BOLD,14));
+		jp_center.add(btn[i]);
+	    btn[i].addActionListener(this);//给按钮注册监听器
+      }
+      this.add(jp_center,BorderLayout.CENTER);
+      }
+	
+	
+	//main方法创建一个窗口
+	public static void main(String[] args) {
+		Calculator computer=new Calculator();
+		computer.setVisible(true);
+	}
+	
+	
+	//按钮的事件处理
+ public void actionPerformed(ActionEvent e) {
+	try
+	{
+		//选择Clear(清零)按钮
+		if(e.getSource()==C_Btn) {
+			input_text.setText("0");//把文本框清零
+			input_text.setHorizontalAlignment(JTextField.RIGHT);//文本右对齐
+			str.setLength(0);//情况字符串缓冲区
+       }
+	//相反数：单击”+/-“选择输入的运算数是正数还是负数
+		else if(e.getSource()==btn[4]) {
+			x=Double.parseDouble(input_text.getText().trim());//trim函数去点字符串空格。double精度转换
+			input_text.setText(""+(-x));
+			input_text.setHorizontalAlignment(JTextField.RIGHT);
+		}
+	//单击加号+按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[3]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=0;
+		}
+	//单击减号-按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[9]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=1;
+	   }
+   //单击乘号*按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[15]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=2;
+	}
+	//单击除号/按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[21]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=3;
+		}
+	//单击等号=按钮输出计算结果
+		else if(e.getSource()==btn[23]) {
+			str.setLength(0);
+			switch(z) {
+			case 0:
+				input_text.setText(" "+(x+y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+				break;
+			case 1:
+				input_text.setText(" "+(x-y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+				break;
+			case 2:
+				input_text.setText(" "+(x*y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+	  			break;
+			case 3:
+				input_text.setText(" "+(x/y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+				break;
+			}
+	   }
+		//小数按钮"."
+		else if(e.getSource()==btn[20]) {
+			if(input_text.getText().trim().indexOf('.')!=-1) { }//没有小数点
+			else {
+				if (input_text.getText().trim().equals("0")) { //初始化0
+					input_text.setText(str.append(e.getActionCommand()).toString());
+					input_text.setHorizontalAlignment(JTextField.RIGHT);
+				}
+				else if(input_text.getText().trim().equals("")) { } //初始化为空，不做任何操作
+				else {
+					input_text.setText(str.append(e.getActionCommand()).toString());
+					input_text.setHorizontalAlignment(JTextField.RIGHT);
+				}
+			}
+			y=0d;
+		}
+		//平方根功能
+		else if(e.getSource()==btn[16]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			if(x<0) {
+				input_text.setText("请输入大于0的数");
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setForeground(Color.red);
+			}
+			else {
+				double result =Math.sqrt(Double.valueOf(x));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+			}
+			str.setLength(0);
+			y=0d;
+		}
+		//0按钮
+		else {
+			if(e.getSource()==btn[19]) {
+				if (input_text.getText().trim().equals("0")) { }//文本框为0则不操作
+				else
+					input_text.setText(str.append(e.getActionCommand()).toString());
+				    input_text.setHorizontalAlignment(JTextField.RIGHT);
+				    y=Double.parseDouble(input_text.getText().trim());
+			}
+		//Backspace键
+			else if(e.getSource()==B_Btn) {	
+				if (!input_text.getText().trim().equals("0")) {
+					if(str.length()!=1) {
+						input_text.setText(str.delete(str.length()-1, str.length()).toString());
+						input_text.setHorizontalAlignment(JTextField.RIGHT);
+					}
+					else {
+						input_text.setText("0");
+						input_text.setHorizontalAlignment(JTextField.RIGHT);
+					    str.setLength(0);
+					}
+				}
+		 y=Double.parseDouble(input_text.getText().trim());
+			}
+			else {
+				input_text.setText(str.append(e.getActionCommand()).toString());
+			    input_text.setHorizontalAlignment(JTextField.RIGHT);
+			    y=Double.parseDouble(input_text.getText().trim());
+			}
+		}
+	}
+	catch(NumberFormatException e1) {
+		input_text.setText("数字格式异常");
+		input_text.setHorizontalAlignment(JTextField.RIGHT);
+		input_text.setForeground(Color.red);
+	}
+	catch(StringIndexOutOfBoundsException e1) {
+		input_text.setText("字符串索引越界");
+		input_text.setHorizontalAlignment(JTextField.RIGHT);
+		input_text.setForeground(Color.red);
+	}
+	save();
+	}
+	
+	//保存方法
+	private void save() {
+		FileOutputStream fos=null;
+		FileReader fr=null;
+		BufferedReader br=null;
+		String s=input_text.getText();
+		try {
+			fos=new FileOutputStream("D:\\calculator.txt");
+			byte[] word=s.getBytes();
+			try {
+				fos.write(word);
+				
+		//利用流读取文件到控制台
+				StringBuffer sa=new StringBuffer("");
+				fr=new FileReader("D:\\\\calculator.txt");
+				br=new BufferedReader(fr);
+				String line =null;
+				while((line=br.readLine()) != null){
+					sa.append(line+"\n");
+					System.out.println(line);
+				}
+			}catch(IOException e) {
+				e.printStackTrace();
+			}
+		}catch(FileNotFoundException e) {
+			e.printStackTrace();
+	}finally {
+		try {
+			fos.close();
+		}catch(IOException e) {
+			e.printStackTrace();
+		}
+	}
+	}
+}
\ No newline at end of file
diff --git a/src/java2020spring/Calculator5.java b/src/java2020spring/Calculator5.java
new file mode 100644
index 0000000000000000000000000000000000000000..88842922778cca1fc8a91571c6302d814910f9a3
--- /dev/null
+++ b/src/java2020spring/Calculator5.java
@@ -0,0 +1,318 @@
+package java2020spring;
+
+
+import java.awt.event.*;
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.EventQueue;
+import java.awt.GridLayout;
+
+import javax.swing.JFrame;
+import javax.swing.JPanel;
+import javax.swing.border.EmptyBorder;
+import javax.swing.JTextField;
+import javax.swing.JButton;
+
+
+public class Calculator5 extends JFrame implements ActionListener{
+
+	private JPanel contentPane;
+	private JTextField input_text;//添加文本框
+	String []labels= {"7","8","9","+","±","Back",
+            "4","5","6","－","1/x","C",
+            "1","2","3","×","√","CE",
+            "%","0",".","÷","x²","="};//给按钮添加文字内容
+	JButton buttons[]=new JButton[labels.length];
+	private boolean firstDigit=true;
+	private String operation=null;//可变字符串，显示屏所显示的字符串
+	Double num1,num2;//定义两个操作数
+	
+	
+	public static void main(String[] args) {
+		EventQueue.invokeLater(new Runnable() {
+			public void run() {
+				try {
+					Calculator5 frame = new Calculator5();
+					frame.setVisible(true);
+					frame.setTitle("欢迎使用计算器");
+				} catch (Exception e) {
+					e.printStackTrace();
+				}
+			}
+		});
+	}
+
+    
+	public Calculator5() {
+		
+		setVisible(true);
+		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		setBounds(100, 100, 540, 300);
+		
+		Color color1=new Color(248,250,216);//按钮颜色设置
+		
+		
+		contentPane = new JPanel();//初始化面板
+		
+		contentPane.setBorder(new EmptyBorder(10, 10,10, 10));
+		
+		contentPane.setLayout(new BorderLayout(0, 0));
+		setContentPane(contentPane);
+		
+		input_text = new JTextField();
+		contentPane.add(input_text, BorderLayout.NORTH);//将文本框添加至面板
+		input_text.setPreferredSize(new Dimension(400,50));//设置文本框的大小
+		input_text.setHorizontalAlignment(JTextField.RIGHT);//设置文本框右对齐
+		input_text.setEditable(false);
+		
+		
+		JPanel panel_buttons = new JPanel();
+		contentPane.add(panel_buttons, BorderLayout.CENTER);
+		panel_buttons.setLayout(new GridLayout(4,6,7,7));
+		for(int i=0;i<labels.length;i++) {
+			buttons[i]=new JButton(labels[i]);
+			panel_buttons.add(buttons[i]);
+			buttons[i].setBackground(color1);
+		}
+		for(int i=0;i<labels.length;i++) {
+			buttons[i].addActionListener(this);
+			
+		}
+	}
+	
+	//计算器功能的实现
+		
+	private void clean() {//将文本框清零
+		input_text.setText(null);
+		operation=null;
+		firstDigit=true;
+	} 
+
+public void actionPerformed(ActionEvent e) {
+		String str=e.getActionCommand();
+		String text=input_text.getText();
+		
+		//清除键"C"
+		if(str.equals(labels[11])) {
+			clean();
+			num1=0.0;
+			num2=0.0;
+		}
+		
+		//百分号键"%"
+		else if(str.equals(labels[18])) {
+			if(text.length()==0) {
+				input_text.setText("请输入数字");
+				operation=null;
+				firstDigit=true;
+			}
+			else if("0123456789.".indexOf(text)==-1) {
+			Double percentage=Double.parseDouble(text);
+			percentage=percentage/100;
+			String percentage_result=String.valueOf(percentage);
+			input_text.setText(percentage_result);
+			
+			}
+		}
+		
+		
+		//根号键"√"
+		else if(str.contentEquals(labels[16])) {
+			if(text.length()==0) {
+				input_text.setText("请输入数字");
+				operation=null;
+				firstDigit=true;
+			}
+			else {
+			Double sqrt_str=Double.parseDouble(text);
+			if(text.startsWith("-")) {
+				input_text.setText("负数无法开根");
+				firstDigit=true;
+				//错误处理功能
+			}
+			else{
+				sqrt_str=Math.sqrt(sqrt_str);
+				input_text.setText(String.valueOf(sqrt_str));
+			}
+		    }
+		}
+		
+		
+		//平方键"x²"
+		else if(str.equals(labels[22])) {
+			if(text.length()==0) {
+				input_text.setText("请输入数字");
+				operation=null;
+				firstDigit=true;
+			}
+			else {
+			Double square=Double.parseDouble(text);
+			square=square*square;
+			String square_result=String.valueOf(square);
+			input_text.setText(square_result);
+			}
+		}
+		
+		
+		
+		//取倒数键"1/x"
+		else if(str.equals(labels[10])) {
+			if(text.length()==0) {
+				input_text.setText("请输入数字");
+				operation=null;
+				firstDigit=true;
+			}
+			else {
+				Double ds=Double.parseDouble(text);
+			    if(ds==0.0) {
+				input_text.setText("零没有倒数");//错误处理功能
+				firstDigit=true;
+			    }
+			    
+			    else {
+			    ds=1/ds;
+			  
+			    input_text.setText(String.valueOf(ds));
+			    }
+			}
+
+		}
+		
+		//CE键,在按下加减乘除键等号键前和C键一样的功能
+		else if(str.equals(labels[17])) {
+			
+			if(operation==null) {
+				clean();
+			}
+			else {
+				input_text.setText(null);
+			}
+		}
+		
+		//删除键"Back"
+		else if(str.equals(labels[5])) {
+			int num=text.length();
+			if(text.length()==0) {
+				input_text.setText("请输入数字");
+				operation=null;
+				firstDigit=true;
+			}
+			else {
+				text=text.substring(0,num-1);
+				input_text.setText(text);
+			}
+		}
+		
+		//按钮"1-9"和"."
+		else if("0123456789.".indexOf(str) >= 0) {
+			if(firstDigit==true) {
+				if(str.equals(".")) {
+					input_text.setText("0"+str);
+				}
+				else {
+				input_text.setText(str);
+				}
+			}
+			else if(str=="."&&input_text.getText().indexOf(".")<0) {
+				input_text.setText(input_text.getText()+str);
+			}
+			else if(str!="."){
+				input_text.setText(input_text.getText()+str);
+			}
+			firstDigit=false;
+			}
+		
+		//加减乘除按钮
+		else if("+－×÷".indexOf(str)>=0) {
+			if(operation==null) {
+				num1=Double.valueOf(input_text.getText());
+				input_text.setText(null);
+				firstDigit=true;
+				operation=str;
+			}
+			else {
+				if(text==null) {
+					operation=str;
+					//textField.setText(String.format("%.3f", num1));
+					input_text.setText(String.valueOf(num1));
+				}
+				if(operation.equals(labels[3])) {
+				num1=num1+Double.valueOf(input_text.getText());
+				input_text.setText(null);
+				firstDigit=true;
+				}
+				if(operation.equals(labels[9])) {
+					num1=num1-Double.valueOf(input_text.getText());
+					input_text.setText(null);
+					firstDigit=true;
+					}
+				if(operation.equals(labels[15])) {
+					num1=num1*Double.valueOf(input_text.getText());
+					input_text.setText(null);
+					firstDigit=true;
+					}
+				if(operation.equals(labels[21])) {
+					num1=num1/Double.valueOf(input_text.getText());
+					input_text.setText(null);
+					firstDigit=true;
+					}
+				operation=str;
+		       }
+		}
+		
+		//等于号
+		else if(str.equals(labels[23])) {
+			if(text==null) {
+				num2=0.0;
+			}
+			else {
+				if(operation==null) {
+				num1=Double.valueOf(text);
+				input_text.setText(String.valueOf(num1));
+			    }
+				num2=Double.valueOf(text);
+			
+			if(operation.equals(labels[3])) {
+				num1=num1+num2;
+				input_text.setText(String.valueOf(num1));
+			}
+			if(operation.equals(labels[9])) {
+				num1=num1-num2;
+				input_text.setText(String.valueOf(num1));
+			}
+			if(operation.equals(labels[15])) {
+				num1=num1*num2;
+				input_text.setText(String.valueOf(num1));
+			}
+			if(operation.equals(labels[21])) {
+				if(num2!=0.0) {
+					num1=num1/num2;
+					input_text.setText(String.valueOf(num1));
+				}
+				else{
+					input_text.setText("零不能做除数");
+					firstDigit=true;
+					}
+			}
+			operation=null;
+			}
+		}
+		
+		//正负号
+				else if(str.equals(labels[4])){
+					if(text.length()==0) {
+						input_text.setText("请输入数字");
+						firstDigit=true;
+					}
+					else {
+					Double change=Double.parseDouble(text);
+					change=-change;
+					input_text.setText(String.valueOf(change));
+					}
+		}
+		}
+        }
+	
+
+
diff --git a/src/java2020spring/Computer.java b/src/java2020spring/Computer.java
new file mode 100644
index 0000000000000000000000000000000000000000..1a477be0a3ccab4d5e7a42c340d1b0d5802f035d
--- /dev/null
+++ b/src/java2020spring/Computer.java
@@ -0,0 +1,300 @@
+package java2020spring;
+
+import java.awt.*;
+import javax.swing.*;
+import javax.swing.border.EmptyBorder;
+import javax.swing.text.JTextComponent;
+
+import java.math.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.io.BufferedReader;
+import java.io.FileOutputStream;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.Writer;
+import java.io.IOException;
+import java.io.FileNotFoundException;
+
+public class Computer extends JFrame implements ActionListener{
+	/*北面的控件*/
+	private JPanel jp_north=new JPanel();
+	private JTextField input_text=new JTextField();
+	private JButton B_Btn=new JButton("Backspace");
+	private JButton C_Btn=new JButton("Clear");
+	/*中间的控件*/
+	private JPanel jp_center=new JPanel();
+	private JButton btn[]=new JButton[24];
+	//可变字符串，显示屏所显示的字符串
+	StringBuffer str;
+	
+	//定义两个操作数
+	double x,y;
+	//z表示单击了哪个运算符(0表示+，1表示-，2表示*，3表示/）
+	int z;
+	
+public Computer( )throws HeadlessException{
+	this.init();
+	this.norComponent();
+	this.addCenterButton();
+	this.save();
+	
+	}
+
+	//窗体初始化
+	public void init() {
+		this.setTitle("计算器");
+		this.setBounds(400,200,500,200);//X.Y,W,H
+		this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
+		this.setResizable(false);
+		this.setLayout(new BorderLayout());
+		str=new StringBuffer();//创建一个空字符串缓冲区
+		
+	}
+	
+	//窗体北面设置
+	public void norComponent() {
+		this.input_text.setPreferredSize(new Dimension(300,30));//设置文本框的大小
+		jp_north.add(input_text);
+		jp_north.add(B_Btn);
+		jp_north.add(C_Btn);
+		this.C_Btn.setForeground(Color.RED);//将清空按钮Clear标为红色字体，提醒防误触清空
+		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		this.add(jp_north,BorderLayout.NORTH);
+		 B_Btn.addActionListener(this);
+		 C_Btn.addActionListener(this);
+		
+		
+	}
+	
+	//窗体下方按钮设置
+	private void addCenterButton() {
+	 
+      this.jp_center.setLayout(new GridLayout(4,6));
+      for(int i=0;i<24;i++) {
+    	  String s=""+i;
+    	  btn[i]=new JButton(s);
+      	btn[0]=new JButton("7");
+      	btn[1]=new JButton("8");
+      	btn[2]=new JButton("9") ;
+        btn[3]=new JButton("+") ;
+        btn[4]=new JButton("±") ;
+        btn[5]=new JButton("二进制");
+        btn[6]=new JButton("4");
+        btn[7]=new JButton("5");
+        btn[8]=new JButton("6");
+        btn[9]=new JButton("-");
+        btn[10]=new JButton("1/x");
+        btn[11]=new JButton("八进制");
+        btn[12]=new JButton("1");
+        btn[13]=new JButton("2");
+        btn[14]=new JButton("3");
+        btn[15]=new JButton("*");
+        btn[16]=new JButton("√");
+        btn[17]=new JButton("十进制");
+        btn[18]=new JButton("%");
+        btn[19]=new JButton("0");
+        btn[20]=new JButton(".");
+        btn[21]=new JButton("/");
+        btn[22]=new JButton("x^2");
+        btn[23]=new JButton("=");
+        btn[i].setFont(new Font("楷体",Font.BOLD,14));
+		jp_center.add(btn[i]);
+	    btn[i].addActionListener(this);
+		}
+		this.add(jp_center,BorderLayout.CENTER);
+		
+	}
+	public static void main(String[] args) {
+		Computer computer=new Computer();
+		computer.setVisible(true);
+	}
+	
+ public void actionPerformed(ActionEvent e) {
+	try
+	{
+		//选择Clear(清零)按钮
+		if(e.getSource()==C_Btn) {
+			input_text.setToolTipText("0");//把文本框清零
+			input_text.setHorizontalAlignment(JTextField.RIGHT);//文本右对齐
+			str.setLength(0);//情况字符串缓冲区
+       }
+	//单击”+/-“选择输入的运算数是正数还是负数
+		else if(e.getSource()==btn[4]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			input_text.setText(""+(-x));
+			input_text.setHorizontalAlignment(JTextField.RIGHT);
+		}
+	//单击加号+按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[3]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=0;
+		}
+	//单击减号-按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[9]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=1;
+	   }
+   //单击乘号*按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[15]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=2;
+	}
+	//单击除号/按钮获得x的值和z的值并清空y的值
+		else if(e.getSource()==btn[21]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			str.setLength(0);
+			y=0d;
+			z=3;
+		}
+	//单击等号=按钮输出计算结果
+		else if(e.getSource()==btn[23]) {
+			str.setLength(0);
+			switch(z) {
+			case 0:
+				input_text.setText(""+(x+y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+				break;
+			case 1:
+				input_text.setText(""+(x-y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+				break;
+			case 2:
+				input_text.setText(""+(x*y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+				break;
+			case 3:
+				input_text.setText(""+(x/y));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+				break;
+			}
+				}
+		//小数按钮"."
+		else if(e.getSource()==btn[20]) {
+			if(input_text.getText().trim().indexOf('.')!=-1) {}//没有小数点
+			else {
+				if (input_text.getText().trim().equals("0")) { //初始化0
+					input_text.setText(str.append(e.getActionCommand()).toString());
+					input_text.setHorizontalAlignment(JTextField.RIGHT);
+				}
+				else if(input_text.getText().trim().equals("")) {} //初始化空
+				else {
+					input_text.setText(str.append(e.getActionCommand()).toString());
+					input_text.setHorizontalAlignment(JTextField.RIGHT);
+				}
+			}
+			y=0d;
+		}
+		//平方根功能
+		else if(e.getSource()==btn[16]) {
+			x=Double.parseDouble(input_text.getText().trim());
+			if(x<0) {
+				input_text.setText("数字格式异常");
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setForeground(Color.red);
+			}
+			else {
+				double result =Math.sqrt(Double.valueOf(x));
+				input_text.setHorizontalAlignment(JTextField.RIGHT);
+				input_text.setFont(new Font("楷体",Font.BOLD,12));
+				input_text.setForeground(Color.blue);
+			}
+			str.setLength(0);
+			y=0d;
+		}
+		//0按钮
+		else {
+			if(e.getSource()==btn[19]) {
+				if (input_text.getText().trim().equals("0")) {}//文本框为0则不操作
+				else
+					input_text.setText(str.append(e.getActionCommand()).toString());
+				    input_text.setHorizontalAlignment(JTextField.RIGHT);
+				    y=Double.parseDouble(input_text.getText().trim());
+			}
+		//Backspace键
+			else if(e.getSource()==B_Btn) {	
+				if (!input_text.getText().trim().equals("0")) {
+					if(str.length()!=1) {
+						input_text.setText(str.delete(str.length()-1, str.length()).toString());
+						input_text.setHorizontalAlignment(JTextField.RIGHT);
+					}
+					else {
+						input_text.setText("0");
+						input_text.setHorizontalAlignment(JTextField.RIGHT);
+					    str.setLength(0);
+					}
+				}
+		 y=Double.parseDouble(input_text.getText().trim());
+			}
+			else {
+				input_text.setText(str.append(e.getActionCommand()).toString());
+			    input_text.setHorizontalAlignment(JTextField.RIGHT);
+			    y=Double.parseDouble(input_text.getText().trim());
+			}
+		}
+	}
+	catch(NumberFormatException e1) {
+		input_text.setText("数字格式异常");
+		input_text.setHorizontalAlignment(JTextField.RIGHT);
+		input_text.setForeground(Color.red);
+	}
+	catch(StringIndexOutOfBoundsException e1) {
+		input_text.setText("字符串索引越界");
+		input_text.setHorizontalAlignment(JTextField.RIGHT);
+		input_text.setForeground(Color.red);
+	}
+	save();
+	}
+	
+	//保存方法
+	private void save() {
+		FileOutputStream fos=null;
+		FileReader fr=null;
+		BufferedReader br=null;
+		String s=input_text.getText();
+		try {
+			fos=new FileOutputStream("D:\\calculator.txt");
+			byte[] word=s.getBytes();
+			try {
+				fos.write(word);
+				
+		//利用流读取文件到控制台
+				StringBuffer sa=new StringBuffer("");
+				fr=new FileReader("D:\\\\calculator.txt");
+				br=new BufferedReader(fr);
+				String line =null;
+				while((line=br.readLine()) != null){
+					sa.append(line+"\n");
+					System.out.println(line);
+				}
+			}catch(IOException e) {
+				e.printStackTrace();
+			}
+		}catch(FileNotFoundException e) {
+			e.printStackTrace();
+	}finally {
+		try {
+			fos.close();
+		}catch(IOException e) {
+			e.printStackTrace();
+		}
+	}
+	}
+
+
+
+	}
\ No newline at end of file
diff --git a/src/java2020spring/Test.java b/src/java2020spring/Test.java
deleted file mode 100644
index fc09c195f566d0e707f5e8a2f05fd168069c73a7..0000000000000000000000000000000000000000
--- a/src/java2020spring/Test.java
+++ /dev/null
@@ -1,10 +0,0 @@
-package java2020spring;
-
-public class Test {
-
-	public static void main(String[] args) {
-		System.out.println("Hello world!");
-
-	}
-
-}