Thread: problem connecting sql server to java

Hi im learning java and after learning about java spring and spring boot i kinda forgot how to proporley connect java to sql on native java.
Im working on an assigment where we were givin a connection pool class which we use to connect to our database,but something isnt working for me

Here is the connection pool code (relevent part)

 
public class ConnectionPool {
	private static ConnectionPool instance = new ConnectionPool();
	private ArrayList<Connection> connections = new ArrayList<>();
	private static final int MAX_CONNECTIONS = 5;
 
	private ConnectionPool() {
		try {
			Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
 
			for (int i = 0; i < MAX_CONNECTIONS; i++) {
 
				try {
					Connection c = DriverManager.getConnection(
							"jdbc:sqlserver://localhost;databaseName=Coupon data;integratedSecurity=true");
					connections.add(c);
				} catch (SQLException e) {
 
				}
 
			}
		} catch (ClassNotFoundException e1) {
			System.out.println(e1.getMessage());
		}
	}

and here is my classDBDAO for example

 
public class CompanyDBDAO implements CompanyDAO {
	private ConnectionPool pool = ConnectionPool.getInstance();
 
	@Override
	public void addCompany(Company company) throws SQLException {
		Connection con = pool.getConnection();
		try {
			PreparedStatement st = con.prepareStatement("insert into companies values(?, ?, ?)");
			st.setString(1, company.getName());
			st.setString(2, company.getEmail());
			st.setString(3, company.getPassword());
			st.execute();
 
		} catch (SQLException e) {
			throw new SQLException(e.getMessage());
		} finally {
			pool.returnConnection(con);
		}
	}

and my main

public static void main(String[] args) {
 
		CompanyDBDAO comdb = new CompanyDBDAO();
 
		try {
			comdb.addCompany(new Company("Company1", "blah1@gmail", "1"));
			comdb.addCompany(new Company("Company2", "blah2@gmail", "12"));
			comdb.addCompany(new Company("Company3", "blah3@gmail", "123"));
 
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

When i try to run my main prog all i get in my console is
"com.microsoft.sqlserver.jdbc.SQLServerDriver"
and no change to my databse.What am i forgetting?

If its the one in the connection pool class ive edited,still no progress

Originally Posted by Norm

What does this print?

		} catch (ClassNotFoundException e1) {
			System.out.println(e1.getMessage());
		}

A clearer message might be shown from this:
System.out.println("CNFE " + e1.getMessage());
Then you would know where it came from.


From where?

I think The message says it can't find a server.

Error was solved via
https://kb.sos-berlin.com/pages/view...ageId=17499564

Thanks for the help!