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I can't connect to sql anywhere 16 database

I have been try to connect with a sql anywhere (v. 16) but what i get is
(java.sql.SQLException: [Sybase][JDBC Driver][SQL Anywhere]Database server not found) error.
This is my code:
public class DBConnection {
private LoginGUI loginGUI;
protected Connection conn;
String dbName = "CPO";
public DBConnection(LoginGUI loginGUI) {
this.loginGUI=loginGUI;
String user = loginGUI.getUsernameStr();
String passwd = loginGUI.getPasswordStr();
String dbUrl = "jdbc:sqlanywhere:uid=" + user + ";pwd=" + passwd + ";eng=demo";
try {
conn = DriverManager.getConnection (dbUrl);
loginGUI.getLoginFrame().setVisible(false);
GUI gui = new GUI();
} catch (SQLException e) {
System.err.println("Can't connect to database");
System.err.println("(" + e + ")\n");
}
}
public Connection connection() {
return this.conn;
}
}

If you're using the JDBC driver for SQL Anywhere 16, you need to change it to the following:
jdbc:sybase:Tds:[server-ip]:[port]/[dbName]
See SAP's documentation about this.
Alternatively you might check out the open source JDBC driver jtds that supports SQL Anywhere as well. In that case the connection string would be
jdbc:jtds:sybase://[server-ip]:[port]/[dbName]

How can I get the values from the main method to be accessed by the getConnection method?

I am trying to get the values that the main method would have produced and use them in the getConnection method. However when I try to access the getConnection method, null values are being returned.
I want to use the ConnectionManager class to connect to the database.
Code below.
public class ConnectionManager {
public static String database;
public static String dbuser;
public static String dbpassword;
public static void main(String args[]) {
Properties prop = new Properties();
InputStream input = null;
try {
input = new FileInputStream("config.properties");
// load a properties file
prop.load(input);
database = prop.getProperty("database");
dbuser = prop.getProperty("dbuser");
dbpassword = prop.getProperty("dbpassword");
System.out.println(database);
} catch (IOException ex) {
ex.printStackTrace();
} finally {
if (input != null) {
try {
input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public static String url = "jdbc:mysql://localhost:3306/" + database;
private static String driverName = "com.mysql.jdbc.Driver";
private static String username = dbuser;
private static String password = dbpassword;
private static Connection con;
public static Connection getConnection() {
try {
Class.forName(driverName);
try {
con = DriverManager.getConnection(url, username, password);
} catch (SQLException ex) {
// log an exception. For example:
System.out.println("Failed to create the database connection.");
System.out.println(url + " " + username + " " + password);
}
} catch (ClassNotFoundException ex) {
System.out.println("Your driver has not been found.");
}
return con;
}
}

You just have to call the getConnection() method with parameters.
public static Connection getConnection(String url, String username, String password) {
/* Your code here */
}
And then, call this method.
Connection connection = getConnection(url, username, password);

Static c fields are initialized once when the class is loaded. The Connection fields are set to the ConnectionManager fields once, when they are still null.
To "fix" your problem, have your code in Connection use the fields in ConnectionManager:
con = DriverManager.getConnection(url, ConnectionManager.dbuser, ConnectionManager.dbpassword);

You're getting null argument values in DriverManager.getConnection(url, username, password) calling cause you have declared them as static fields.
So you initialize them as nulls before you read the particular values from the config.properties
Let's follow the flow:
Static initialization step:
private static String username = dbuser; //username==null; dbuser==null;
private static String password = dbpassword; //password==null; dbpassword==null
private static Connection con; //con==null;
Method main execution:
database = (prop.getProperty("database"));
dbuser = (prop.getProperty("dbuser")); //dbuser="smth"; username==null
dbpassword = (prop.getProperty("dbpassword")); //dbpassword ="smth"; password==null
Method getConnection execution:
con = DriverManager.getConnection(url, username, password); //username==null; //password==null;
P.S.: As it was previously said, it's better to use function with arguments like this:
public static Connection getConnection(String url, String username, String password) {
/* Your code here */
}

connecting Java to MySQL

I'm doing my dissertation on software engineering and im building a small application that makes use of a SQL DB, in this case MySQL. I'm also using the application controller pattern. So the code I have working for retrieving data from the db is;
public static void main(String[] args)
{
try
{
String url = "jdbc:mysql://localhost:3306/tm470_returns_stock_management_system";
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection(url,"root","root");
Statement st = con.createStatement();
ResultSet res = st.executeQuery("SELECT * FROM test_table");
while (res.next())
{
int id = res.getInt("test_id");
String msg = res.getString("test_info");
System.out.println(id + "\t" + msg);
}
con.close();
}
catch(Exception e)
{
System.out.println("DB connection unsuccesful");
}
}
I now want to transfer this out of my Main class/string and into my Application Controller Class (which is called Facility).
Now my question is, for every method in my Facility Class that needs to access the DB, do i have to do the full code each time? Or can i create a method within the Facility class that each application method can just call whenever it needs to access the DB. If i can condense all this into a method, can you advise me how to go about it please?
Be gentle with me guys, I am a learner :)

How about adding a utility class like ConnectionUtil and using the static method to access the connection.
import java.sql.Connection;
import java.sql.DriverManager;
public class ConnectionUtil{
static final String url = "jdbc:mysql://localhost:3306/";
static final String dbName = "test";
static final String driver = "com.mysql.jdbc.Driver";
static final String userName = "userparatest";
static final String password = "userparatest";
Connection con = null;
static Connection getConnection() throws Exception {
if(con == null)
{ Class.forName(driver).newInstance();
con = DriverManager.getConnection(url + dbName, userName,password);
}
return con;
}
}
this can be further improved but just providing a start..
just call below whenever you want a statement..
Statement st = ConnectionUtil.getConnection().createStatement();

I would map it as a own class, which is used by your application other classes. When you define it as a singleton you will only need one instance in your complete application

Yes , you can write a method for accessing db and you can reuse it across all the applications.
Keep the following in a method and reuse it.
String url = "jdbc:mysql://localhost:3306/tm470_returns_stock_management_system";
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection(url,"root","root");
Statement st = con.createStatement();
int productID = 6;
String skuCode = "ABC123";
ResultSet res = st.executeQuery("SELECT * FROM test_table");
while (res.next())
{
int id = res.getInt("test_id");
String msg = res.getString("test_info");
System.out.println(id + "\t" + msg);
}

Why i can not connect to mysql db using java

I have used jdbc driver before.But for this piece of program i can't connect to the db.This doesn't throw any exception or anything. Just won't connect. I couldn't find a solution online either.Below is the code i tried to run :( Please help in solving this. Thank you in advance :)
public class HeapMySql<T extends Comparable<T>> implements HeapInterface {
static final String DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost/Heap";
static final String USERNAME = "root";
static final String PASSWORD = "";
private int size = 0 ;
String sql;
static Statement stmt = null;
static Connection conn = null;
static ResultSet rs = null;
public void HeapMySql(){
try
{
sql = "CREATE TABLE testHeap (index integer, value integer);";
stmt.executeUpdate(sql);
System.out.println("Done");
}catch(Exception e){
}
}
public static void main(String [] arg){
try{
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(DB_URL, USERNAME, PASSWORD);
System.out.println("Connected database successfully...");
System.out.println("Creating table in given database..."); //lets create a table in our database
stmt = conn.createStatement();
HeapMySql test1 = new HeapMySql<>();
}catch(ClassNotFoundException | SQLException ex){
}finally{
}

A constructor does not have a return type: docs
Remove void from public void HeapMySql() and it will do the work.
Also as said in comments, you should print the stacktrace in your catch blocks. This makes it easy to understand the exception and resolve the problem.

If I use a singleton class for a database connection, can one user close the connection for everybody?

I wrote a singleton class for obtaining a database connection.
Now my question is this: assume that there are 100 users accessing the application. If one user closes the connection, for the other 99 users will the connection be closed or not?
This is my sample program which uses a singleton class for getting a database connection:
public class GetConnection {
private GetConnection() { }
public Connection getConnection() {
Context ctx = new InitialContext();
DataSource ds = ctx.lookup("jndifordbconc");
Connection con = ds.getConnection();
return con;
}
public static GetConnection getInstancetoGetConnection () {
// which gives GetConnection class instance to call getConnection() on this .
}
}
Please guide me.

As long as you don't return the same Connection instance on getConnection() call, then there's nothing to worry about. Every caller will then get its own instance. As far now you're creating a brand new connection on every getConnection() call and thus not returning some static or instance variable. So it's safe.
However, this approach is clumsy. It doesn't need to be a singleton. A helper/utility class is also perfectly fine. Or if you want a bit more abstraction, a connection manager returned by an abstract factory. I'd only change it to obtain the datasource just once during class initialization instead of everytime in getConnection(). It's the same instance everytime anyway. Keep it cheap. Here's a basic kickoff example:
public class Database {
private static DataSource dataSource;
static {
try {
dataSource = new InitialContext().lookup("jndifordbconc");
}
catch (NamingException e) {
throw new ExceptionInInitializerError("'jndifordbconc' not found in JNDI", e);
}
}
public static Connection getConnection() {
return dataSource.getConnection();
}
}
which is to be used as follows according the normal JDBC idiom.
public List<Entity> list() throws SQLException {
List<Entity> entities = new ArrayList<Entity>();
try (
Connection connection = Database.getConnection();
PreparedStatement statement = connection.prepareStatement("SELECT id, foo, bar FROM entity");
ResultSet resultSet = statement.executeQuery();
) {
while (resultSet.next()) {
Entity entity = new Entity();
entity.setId(resultSet.getLong("id"));
entity.setFoo(resultSet.getString("foo"));
entity.setBar(resultSet.getString("bar"));
entities.add(entity);
}
}
return entities;
}
See also:
Is it safe to use a static java.sql.Connection instance in a multithreaded system?

Below code is a working and tested Singleton Pattern for Java.
public class Database {
private static Database dbIsntance;
private static Connection con ;
private static Statement stmt;
private Database() {
// private constructor //
}
public static Database getInstance(){
if(dbIsntance==null){
dbIsntance= new Database();
}
return dbIsntance;
}
public Connection getConnection(){
if(con==null){
try {
String host = "jdbc:derby://localhost:1527/yourdatabasename";
String username = "yourusername";
String password = "yourpassword";
con = DriverManager.getConnection( host, username, password );
} catch (SQLException ex) {
Logger.getLogger(Database.class.getName()).log(Level.SEVERE, null, ex);
}
}
return con;
}
While getting Connection in any Class simply use below line
Connection con = Database.getInstance().getConnection();
Hope it may help :)

package es.sm2.conexion;
import java.sql.Connection;
import java.sql.DriverManager;
public class ConexionTest {
private static Connection conn = null;
static Connection getConnection() throws Exception {
if (conn == null) {
String url = "jdbc:mysql://localhost:3306/";
String dbName = "test";
String driver = "com.mysql.jdbc.Driver";
String userName = "userparatest";
String password = "userparatest";
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url + dbName, userName, password);
}
return conn;
}
}
To close Connection
public static void closeConnection(Connection conn) {
try {
conn.close();
} catch (SQLException e) {
}
}
To call to the connection:
package conexion.uno;
import java.sql.*;
import es.sm2.conexion.ConexionTest;
public class LLamadorConexion {
public void llamada() {
Connection conn = null;
PreparedStatement statement = null;
ResultSet resultado = null;
String query = "SELECT * FROM empleados";
try {
conn = ConexionTest.getConnection();
statement = conn.prepareStatement(query);
resultado = statement.executeQuery();
while (resultado.next()) {
System.out.println(resultado.getString(1) + "\t" + resultado.getString(2) + "\t" + resultado.getString(3) + "\t" );
}
}
catch (Exception e) {
System.err.println("El porque del cascar: " + e.getMessage());
}
finally {
ConexionTest.closeConnection(conn);
}
}
}

Great post, farhangdon! I, however, found it a little troublesome because once you close the connection, you have no other way to start a new one. A little trick will solve it though:
Replace if(con==null) with if(con==null || con.isClosed())

import java.sql.Connection;
import java.sql.DriverManager;
public class sql11 {
static Connection getConnection() throws Exception {
Class.forName("com.mysql.jdbc.Driver");
Connection c = DriverManager.getConnection("jdbc:mysql://localhost:3306/ics", "root", "077");
return c;
}
}