=== Main Class ===



public class CentralServer {

    protected static final Map<Integer, StudentDetails> nameCache = new HashMap<Integer, StudentDetails>();
    public static int name = "";

    public static void main(String[] args) {
        System.out.println("Loading...");
        loadStudentDetails();
        System.out.println("Please enter the student's ID");
        boolean retry = false;
        while (!retry) {
            try {
                name = System.console().readLine();
                final StudentDet newName;
                try {
                    newName = nameCache.get(name);
                    retry = true;
                } catch (Exception ex) {
                    retry = false;
                    System.out.println("Invalid input. Please re-enter.");
                }
            } catch (Exception e) {
                System.out.println("Invalid input. Please re-enter.");
            }
        }

        final StringBuilder sb = new StringBuilder("Student Details...");
        sb.append("Name...").append(newName.getName());
        sb.append("Age...").append(newName.getAge());

        System.out.println(sb.toString());
    }

    public static void loadStudentDetails() {
        Connection con = DatabaseConnection.getConnection();
        try {
            PreparedStatement ps = con.prepareStatement("SELECT * FROM `students`");
            ResultSet rs = ps.executeQuery();
            while (rs.next()) {
                StudentDetails info = new StudentDetails();
                int studentID = rs.getInt("id");
                info.name = rs.getInt("name");
                info.age = rs.getByte("age"));
                nameCache.put(studentID, info);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static class StudentDetails {
        private String name;
        private byte age;

        private NpcInfo() {
        }

        public String getName() {
            return name;
        }

        public byte getAge() {
            return age;
        }
    }
}



== Database class ===

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Collection;
import java.util.LinkedList;

public class DatabaseConnection {

    // Alter this.
    private static String dbDriver = "com.mysql.jdbc.Driver",
            dbUrl = "jdbc:mysql://localhost:3306/database_name?autoReconnect=true",
            dbUser = "root",
            dbPass = "";

    private static final ThreadLocal<Connection> connections = new ThreadLocalConnection();

    public static final Connection getConnection() {
        return connections.get();
    }

    public static final void closeAll() throws SQLException {
        for (final Connection con : ThreadLocalConnection.allConnections) {
            con.close();
        }
    }

    private static final class ThreadLocalConnection extends ThreadLocal<Connection> {

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

        @Override
        protected final Connection initialValue() {
            try {
                Class.forName(dbDriver);
            } catch (final ClassNotFoundException e) {
                System.err.println("ERROR" + e);
            }
            try {
                final Connection con = DriverManager.getConnection(dbUrl, dbUser, dbPass);
                allConnections.add(con);
                return con;
            } catch (SQLException e) {
                System.err.println("ERROR" + e);
                return null;
            }
        }
    }
}