CODEWITHSUNDEEP
javamysqlsqljdbc
André Ferraz
André Ferraz

Reputation: 1521

Working with Java & SQL

I have been playing around with JDBC drivers. I would like some advice from the experience code masters out there. I was wondering if this is a good way to find if am connected to a database. If it is not, could someone let me know how would they do it?

Connection con = null;

    try {
         con = DriverManager.getConnection("jdbc:mysql://localhost/"+database+"?+user="+user+"&password="+password);
    } catch (SQLException e) {
         System.out.println(e.getMessage());
            if (con != null) {
                System.out.println("hello");
            } else {
                System.out.println("Not Connected!");
            }
    }

I would really appreciate all helpful comments. Many thanks in advance.

Upvotes: 1

Views: 177

Answers (3)

hmjd
hmjd

Reputation: 122011

If the getConnection method returns normally, and does not throw an exception, then a connection to the database has been made. The logic within the catch clause is unrequired, because if an exception is caught a connection was not established.

The returned Connection object must be close()d (as many of the JDBC classes must, such as Statements and ResultSets for example). Assuming Java7, a convenient way to ensure the Connection is closed is using the try-with-resources statement:

try (Connection con = DriverManager.getConnection(...))
{
}
catch (final SQLException e)
{
}

As stated by SnakeDoc in the comments this may be impractical in production systems because establishing a connection to the database is a typically expensive operation.

Upvotes: 2

ktm5124
ktm5124

Reputation: 12123

The JDBC API will perform these checks for you. Whenever you perform a database operation, such as opening a connection, executing a statement, it will check to see if the connection is valid. If not it will throw an exception.

For example, the method Connection.createStatement throws the following:

SQLException - if a database access error occurs or this method is called on a closed connection

All you have to do is some basic exception handling. Surrounding your JDBC calls with try-catch blocks is one way do this. You could also throw the exception and handle it somewhere else.

Upvotes: 1

Adam Carlin
Adam Carlin

Reputation: 244

That's definitely a good way of doing it! If conn can't be initialised it's either your connection string that is wrong or the database is down.

Upvotes: -1

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