Code for Network Programming Project 2

Client.java

import java.io.*;
import java.net.*;
import java.sql.*;
import java.util.*;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;
 
class Client {
      private static int port = 12345; 
      private static String host = "localhost"; 

      public static void main(String[] args) throws IOException, SQLException, ClassNotFoundException {

            Socket server = null;
            PrintWriter out = null;

            try {
                  server = new Socket(host, port);
                  out = new PrintWriter(server.getOutputStream(), true);
            } catch (UnknownHostException e) {
                  System.err.println(e);
                  System.exit(1);
            }

            boolean checkExit = false;
            do{
                  checkExit = false;
                  System.out.println("\n================== Menu ==================");
                  System.out.println("1.) Show all sudents's score");
                  System.out.println("2.) Add sudents's score");
                  System.out.println("3.) Delete sudents's score");
                  System.out.println("4.) Search sudents's score");
                  System.out.println("5.) Exit");
                  System.out.print("Enter your choice: ");
                  BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
                  String msg = stdIn.readLine();
                 
                  if(msg.equals("1")){
                	  showAll();
                  }else if(msg.equals("2")){
                	  addScore();
                  }else if(msg.equals("3")){
                	  deleteScore();
                  }else if(msg.equals("4")){
                	  searchStudent();
                  }else if(msg.equals("5")){
                	  server.close();
                      System.exit(0);
                      checkExit=true;
                  }
            }while(checkExit=false);
      }
      
      public static void showAll() throws IOException, SQLException, ClassNotFoundException{
  		try {
  			Class.forName("com.mysql.jdbc.Driver");
  			String url ="jdbc:mysql://localhost:3306/testdb";
  			Connection con = (Connection) DriverManager.getConnection(url,"root","");
  			Statement st = (Statement) con.createStatement();
  			ResultSet rs = st.executeQuery("SELECT * FROM student ORDER BY studentID ASC");
  			
  			System.out.println("\n============= Show all students score =============\n");
  			int count = 0;
  			while (rs.next()) {
  				count++;
  				System.out.println(count + ".) " + "Student ID = " +rs.getString(1)+ ",  Score = "+rs.getString(2));
  			}	
  		} catch (Exception e) {
  			System.out.println(e);
  		} finally{
        	main(null);
        }
  	}

      public static void addScore() throws IOException, SQLException, ClassNotFoundException{
            Scanner kb = new Scanner(System.in);
            System.out.print("Enter ID to add: ");
            String id = kb.nextLine();
            try {
                  Class.forName("com.mysql.jdbc.Driver");
                  String url ="jdbc:mysql://localhost:3306/testdb";
                  Connection con = (Connection) DriverManager.getConnection(url,"root","");

                  Statement st = (Statement) con.createStatement();
                  ResultSet rs = st.executeQuery("SELECT * FROM student WHERE studentID = '" + id + "'");
            
                  int count = 0;
                  while (rs.next()) {
                	  count++;
                  }
                  
                  if(count==0){
                	  try {
                		  System.out.print("Enter Score to add: ");
                		  int score = kb.nextInt();
                  	  	  String insertMySQL = "INSERT INTO student (studentID, studentScore) VALUES (" + id +"," + score + ")";
                  	  	  Statement statement = (Statement) con.createStatement();
                  	      statement.execute(insertMySQL);
                          System.out.println("Score is added to database");
                          main(null);
	                  } catch (SQLException e) {
	                	  System.out.println(e.getMessage());
	                  }
                  }else{
                	  System.out.println("This id is added already in database");
                  }
                  
                  System.out.println();  
                  
            } catch (Exception e) {
                  System.out.println(e);
            } finally{
            	main(null);
            }
      }
      
      public static void deleteScore() throws IOException, SQLException, ClassNotFoundException{
    	  Scanner kb = new Scanner(System.in);
    	  System.out.print("Enter ID: ");
    	  String id = kb.nextLine();
    	  
    	  Class.forName("com.mysql.jdbc.Driver");
          String url ="jdbc:mysql://localhost:3306/testdb";
          Connection con = (Connection) DriverManager.getConnection(url,"root","");
    	  Statement st = (Statement) con.createStatement();
          ResultSet rs = st.executeQuery("SELECT * FROM student WHERE studentID = '" + id + "'");
    
          int count = 0;
          while (rs
        		  .next()) {
        	  count++;
          }
          if(count==0){
        	  System.out.print("The database has no thid id!");
        	  main(null);
          }else{
        	  try {
    	    	  String deleteTableSQL = "DELETE FROM student WHERE studentID = "+id;
    	    	  try {
    		    	  Statement statement = (Statement) con.createStatement();
    		    	  statement.execute(deleteTableSQL);
    		    	  System.out.println("Score is deleted from database");
    	    	  } catch (SQLException e) {
    	    		  System.out.println(e.getMessage());
    	    	  }
    	    	  System.out.println();
    	    	  System.out.println("Connection database completed !!");	
        	  } catch (Exception e) {
        		  System.out.println(e);
        	  } finally{
              	main(null);
              }
          }
    	  
      }
      
      public static void searchStudent() throws IOException, SQLException, ClassNotFoundException{
  		Scanner kb = new Scanner(System.in);
  		System.out.print("Enter ID to search: ");
  		String id = kb.nextLine();
  		
  		try {
  			Class.forName("com.mysql.jdbc.Driver");
  			String url ="jdbc:mysql://localhost:3306/testdb";
  			Connection con = (Connection) DriverManager.getConnection(url,"root","");
  			Statement st = (Statement) con.createStatement();
  			ResultSet rs = st.executeQuery("SELECT * FROM student WHERE studentID = "+ id);
  			
  			System.out.println("\n============= Show search student score =============\n");
  			while (rs.next()) {
  				System.out.println("\tStudent ID = " +rs.getString(1)+ ",  Score :"+rs.getString(2));
  			}
  			
  		} catch (Exception e) {
  			System.out.println(e);
  		} finally{
        	main(null);
        }
  	}
}

Server.java

import java.net.ServerSocket;
import java.net.Socket;
 
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
 
class Server {
    private static int port = 12345; /* port the server listens on */
 
    public static void main (String[] args) throws IOException {
        ServerSocket server = null;
        try {
            server = new ServerSocket(port); /* start listening on the port */
            System.out.println("\nServer is waiting for connecting from Client");
 
        } catch (IOException e) {
            System.err.println("Could not listen on port: " + port);
            System.err.println(e);
            System.exit(1);
        }
 
        Socket client = null;
        try {
            client = server.accept();
            System.out.println("Client is connected with Server");
        } catch (IOException e) {
            System.err.println("Accept failed.");
            System.err.println(e);
            System.exit(1);
        }
 
        BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
 
        String msg= null;
        while(true){
        		msg = in.readLine();
	        	System.out.println("Client choose: " + msg);
 
	            if(msg.equals("1")){
	            	String[] splitString = msg.split(" ");
	            }
        }
        
    }
}