JAVA: Connection to MySQL

have 2 files:
- KoneksiMysql.java
- and menu.java

database: akademik
tabel : mahasiswa (field: nim,nama )

====================================
name: KoneksiMysql.java

//package koneksi.mysql;
import java.sql.*;

public class KoneksiMysql {
String url, usr, pwd, dbn;
public KoneksiMysql (String dbn) {
this.url = "jdbc:mysql://localhost/" + dbn;
this.usr = "root";
this.pwd = "";
}

public KoneksiMysql (String host, String user, String pass, String dbn) {
this.url = "jdbc:mysql://" + host + "/" + dbn;
this.usr = user;
this.pwd = pass;
}

public Connection getConnection() {
Connection con = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection(this.url, this.usr, this.pwd);
} catch (ClassNotFoundException e) {
System.out.println ("Error #1 : " + e.getMessage());
System.exit(0);
} catch (SQLException e) {
System.out.println ("Error #2 : " + e.getMessage());
System.exit(0);
}
return con;
}
/*
public static void main (String args[]) {
KoneksiMysql kon = new KoneksiMysql ("akademik");
Connection c = kon.getConnection();
}
*/
}


=================================

name: menu.java



import java.sql.*;
import java.io.*;

class menu {
public static void main(String args[]) throws IOException{
BufferedReader stdin=new
BufferedReader(new InputStreamReader(System.in));

String buff;
int pilih;

try {
KoneksiMysql kon = new KoneksiMysql ("akademik");
Connection c = kon.getConnection();
pilih=0;
while(pilih<5) {
System.out.println(" Menu : ");
System.out.println(" 1. Lihat Data ");
System.out.println(" 2. Tambah Data ");
System.out.println(" 3. Hapus Data ");
System.out.println(" 4. Update Data ");
System.out.println(" 5. Exit ");
System.out.print(" Pilih nomor : ");
buff = stdin.readLine();
pilih=Integer.parseInt(buff);
ResultSet hasilQuery = null;
Statement stm = c.createStatement();

switch(pilih){
case 1:
{
hasilQuery = stm.executeQuery("SELECT * FROM mahasiswa");

while (hasilQuery.next()) {
String nim_mahasiswa = hasilQuery.getString("nim");
String nama_mahasiswa = hasilQuery.getString("nama");
System.out.println(nim_mahasiswa+" -> " + nama_mahasiswa); }

break;
}
case 2:
{
String nim_t, nama_t;
System.out.print("nim : ");
nim_t = stdin.readLine();
System.out.print("nama : ");
nama_t = stdin.readLine();
String sql="INSERT into mahasiswa values('"+nim_t+"','"+nama_t+"')";
stm.executeUpdate(sql);
break;
}
case 3:
{
String nim_h;
System.out.print("nim : ");
nim_h = stdin.readLine();
String sqlh="DELETE from mahasiswa where nim = '"+nim_h+"'";
stm.executeUpdate(sqlh);
break;
}
case 4:
{
String nim_u,nama_u;
System.out.print("nim : ");
nim_u = stdin.readLine();
hasilQuery = stm.executeQuery("SELECT * FROM mahasiswa where nim = '" + nim_u + "'");
while (hasilQuery.next()) {
String nm_mahasiswa = hasilQuery.getString("nama");
System.out.println("Nama : " + nm_mahasiswa);
}

System.out.print("Nama Baru : ");
nama_u = stdin.readLine();

String sqlu="UPDATE mahasiswa set nama='" + nama_u + "' where nim = '" + nim_u + "'";
stm.executeUpdate(sqlu);
break;
}
default:
{
System.out.println("Bye");
break; }

}
}
c.close();

}
catch (Exception e) {
System.out.println("Error : "+e);
}
}
}