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November 28th, 2012, 02:57 PM

yoyo123123

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Join Date: Nov 2012

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Homework - Workers List

Hello, I got homework to make a worker list, I have to make it with 3 files:
1-MYSQL connection
2-WorkerLoad - loads from the database
3-WorkersInfo - prints the database info
I succeded to the first 2 but having troubles with the third, help please??

the first file is:

PHP Code:


		
			
 package connection;



import java.sql.*;

import java.util.Collection;

import java.util.LinkedList;



public class MYSQLconnection{

    private static ThreadLocal<Connection> con = new LocalConnection();

    

    public static Connection getConnection() {

        return con.get();

    }

    

    public static void closeAll() throws SQLException {

        for (Connection con : LocalConnection.allConnections) {

            con.close();

        }

    }

    public static class LocalConnection extends ThreadLocal<Connection> {

        public static Collection<Connection> allConnections = new LinkedList<Connection>();



        @Override

        protected Connection initialValue() {

            String driver = "com.mysql.jdbc.Driver";

            String url = "jdbc:mysql://localhost:3306/";

            String userName = "root";

            String password = "ROOT";

            String dbName = "schoolproject";

            try {

                Class.forName(driver).newInstance();

                Connection conn = DriverManager.getConnection(url+dbName,userName,password);

                System.out.println("Connected to the database");

                allConnections.add(conn);

                return conn;

            } catch (Exception e) {

                e.printStackTrace();

                return null;

            }

        }

    }

}

the second:

PHP Code:


		
			
 package Loads;



import connection.MYSQLconnection;

import Infos.WorkersInfo;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.LinkedList;

import java.util.List;



//id name



public class WorkerLoad {

    private int id;

    private String name;

    private List<WorkersInfos> work = new LinkedList<WorkersInfos>();

    private static WorkerLoad instance = new WorkerLoad();

    

    public void loadFromDb(int workerid) throws SQLException {

        WorkerLoad ret = new WorkerLoad();

        Connection con = MYSQLconnection.getConnection();

        PreparedStatement ps = con.prepareStatement("SELECT * FROM workers WHERE id=?");

        ps.setInt(1, workerid);

        ResultSet rs = ps.executeQuery();

        /*if (!rs.next()) {

            rs.close();

            ps.close();

            System.out.println("something failed"); 

        }*/

        while(rs.next()){

            System.out.println("dfsgdsfgdfsgdfs");

            ret.id = rs.getInt("id");

            ret.name = rs.getString("name");

            System.out.println("worker number "+ret.id);

            final WorkersInfos rank = new WorkersInfos(rs.getInt("id"),rs.getString("name"));

            work.add(rank);



            

        }

        rs.close();

        ps.close();

    }

  

    

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

        WorkerLoad abc = new WorkerLoad();

        abc.loadFromDb(1);

        abc.loadFromDb(2);

        WorkersInfo vvv = new WorkersInfo();

        vvv.check();

        



    }

  

    public static WorkerLoad getInstance() {

        return instance;

    }

        public List<WorkersInfos> getWork() {

        return work;

    }

        public static class WorkersInfos {



        private String namez;

        private int idz;



        public WorkersInfos(int idz, String namez) {

            this.idz = idz;

            this.namez = namez;

        }



        public String getName() {

            return namez;

        }



        public int getId() {

            return idz;

        }

    }

        

        

        

}

the third:

PHP Code:


		
			
 package Infos;







import Loads.WorkerLoad;

import Loads.WorkerLoad.WorkersInfos;

import java.util.Arrays;

import java.util.List;



public class WorkersInfo {

    public void check(){

        StringBuilder ret = new StringBuilder();

        String s = null;

        final List<WorkersInfos> work = WorkerLoad.getInstance().getWork();

        for (WorkersInfos info : work) {

            ret.append("name = ");

            ret.append(info.getName());

            ret.append("id = ");

            ret.append(info.getId());

        }

            s=ret.toString();

            System.out.println(s);         



    }

}

I don't know why, but in the third, the FOR don't work

(sorry for the bad english)

November 28th, 2012, 03:44 PM

bullet

Java Junkie

Join Date: Feb 2004

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Look at the type of the variable

Code:

for (WorkersInfos info : work) {

November 28th, 2012, 03:53 PM

yoyo123123

Registered User

Join Date: Nov 2012

Posts: 4

Time spent in forums: 2 h 38 m 2 sec
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Quote:

Originally Posted by bullet

Look at the type of the variable

Code:

for (WorkersInfos info : work) {

no thats fine, I think the error is :

Code:

    public List<WorkersInfos> getWork() {
        return work;
    }

November 28th, 2012, 04:26 PM

bullet

Java Junkie

Join Date: Feb 2004

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Quote:

Originally Posted by yoyo123123

no thats fine, I think the error is :

Code:

    public List<WorkersInfos> getWork() {
        return work;
    }

In both cases look at the spelling of the type.

November 28th, 2012, 04:39 PM

yoyo123123

Registered User

Join Date: Nov 2012

Posts: 4

Time spent in forums: 2 h 38 m 2 sec
Reputation Power: 0

Quote:

Originally Posted by bullet

In both cases look at the spelling of the type.

it the same spelling as the class

November 28th, 2012, 04:41 PM

bullet

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Quote:

Originally Posted by yoyo123123

it the same spelling as the class

Code:

public class WorkersInfo

November 28th, 2012, 04:46 PM

yoyo123123

Registered User

Join Date: Nov 2012

Posts: 4

Time spent in forums: 2 h 38 m 2 sec
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Quote:

Originally Posted by bullet

Code:

public class WorkersInfo

there is WorkersInfo and WorkersInfos with "s" in the end.
WorkersInfos with "s" is where "work" list *sits* but when I do System.out.Println(getInstance().getWork().size);
it gives me 0 when it needs to give me 2
(while the LoadFromDB , it does give me 2 elements, but when I call to getWork() it gives me 0... I don't know why but it doesn't want to save the list)

November 29th, 2012, 07:22 AM

Revoh

Contributing User

Join Date: Mar 2007

Location: Portugal

Posts: 38

Time spent in forums: 4 Days 6 h 39 m 59 sec
Reputation Power: 8

First of all why did you make such a huge amount of high coupling?

Because your classes don't make much sense it would be correct to have WorkersInfo as an object Worker with id and name.

But anyway.

Could it be since you have made WorkersInfos a static class?

And why do you use this. for set methods and get methos you don't?

P.S. why did you place WorkersInfos inside WorkerLoad?

Last edited by Revoh : November 29th, 2012 at 07:26 AM.

Homework - Workers List

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