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Asked: 2026-05-11T05:22:18+00:00

I have create a getDBConnection method in my Java application. This returns a connection

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I have create a getDBConnection method in my Java application. This returns a connection object, and hence I haven’t closed this connection in this method itself.

Now, I am invoking this method from various methods in my application at regular intervals, and closing them inside a try – finally block. I thought this should free up the connection after use. However, I am seeing a large number of connections opened (about 50) in the MySQL Administrator’s Server Connections tab. 

//Defining a method to retrieve a database connection // PropDemo is a properties class that retrieves Database related values from a file public Connection getDBConnection() {      //Instantiating the Properties object     PropDemo prop = new PropDemo();     Connection con = null;      // Retrieving values from the parameters.properties file     String JdbcDriver = prop.getMessage('JdbcDriver');     String JdbcUrlPrefix = prop.getMessage('JdbcUrlPrefix');     String DBIP = prop.getMessage('DBIP');     String DBName = prop.getMessage('DBName');     String DBUser = prop.getMessage('DBUser');     String DBPassword = prop.getMessage('DBPassword');      try {          // Loading and instantiating the JDBC MySQL connector driver class         Class.forName(JdbcDriver).newInstance();         con = DriverManager.getConnection(JdbcUrlPrefix + DBIP + '/' + DBName, DBUser, DBPassword);             if (con.isClosed())                     Logger.log('Connection cannot be established', 'vm');      } catch (Exception e) {         Logger.log('Exception: ' + e, 'vm');         Logger.log(Logger.stack2string(e), 'vm');     }     return con;  }

I am also closing the associated ResultSet and Statement Objects. What could be missing here?

I am planning to replace all the Statements with PreparedStatements for efficiency and security reasons. Will that help significantly? What else can be done?

EDIT: This is just a core java application that is repeatedly quering for changes in some fields in a MySQL database through MySQL-JDBC connector. I am not using any framework like Spring or Hibernate.

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1 Answer

  1. Your code looks sane.

    That’s how you’re creating a new connection.

    Probably the error is where you close it.

    You should close it in a finally block.

    Some additional questions.

    1) Are you sure those 50 conections come from this program ? Maybe there are some others comming from your same office. To confirm this you would need to stop the program, and look again in your connection monitor.

    2) Does your application uses many connection simultaneously? Probably its a peak when you’re using 50 at the same time.

    If you can post the code where you close the connection. Chances are the problem is there.

    Additionally I would suggest you to use a connection pool. You can build one your self or you can see the results from this page:

    How many JDBC connections in Java?

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