CODEWITHSUNDEEP
javaexceptiontry-catch
Dev
Dev

Reputation: 13753

Try with resources Statement for JDBC in java

Useful piece of code for Hive JDBC:

       Connection con = null;
       Statement stmt = null

        try {
            Class.forName("org.apache.hive.jdbc.HiveDriver");
            con = DriverManager.getConnection(connectionUri, userName, password);
            stmt = con.createStatement();
            stmt.executeUpdate(query);

        } catch (ClassNotFoundException cex) {
            cex.printStackTrace();

        } catch (SQLException e) {
            e.printStackTrace();

        } finally {
            if (stmt != null) {
                try {
                    stmt.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }

            if (con != null) {
                try {
                    con.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

I want to remove try - catch in finally block.

So I tried The try-with-resources Statement.

        try (Class.forName("org.apache.hive.jdbc.HiveDriver");
            Connection con = DriverManager.getConnection(connectionUri, userName, password);
            Statement stmt = con.createStatement();){

            stmt.executeUpdate(query);

        } catch (ClassNotFoundException cex) {
            cex.printStackTrace();

        } catch (SQLException e) {
            e.printStackTrace();
        }

I think this is not the right way.

Class.forName("org.apache.hive.jdbc.HiveDriver") should not be in try. Should I make a separate try-catch for this?

       try {
            Class.forName("org.apache.hive.jdbc.HiveDriver");

        } catch (ClassNotFoundException cex) {
            cex.printStackTrace();
        }
        try (Connection con = DriverManager.getConnection(connectionUri, userName, password);
            Statement stmt = con.createStatement();){

            stmt.executeUpdate(query);

        } catch (SQLException e) {
            e.printStackTrace();
        }

Is this right way or am I missing any thing?

Upvotes: 3

Views: 1553

Answers (2)

Steve C
Steve C

Reputation: 19445

When you're using Java 6 or better and the Apache Hive JDBC driver is JDBC 4 compliant or better* then you do not need the Class.forName("org.apache.hive.jdbc.HiveDriver") stuff at all.

Therefore you can just remove the entire try/catch block from your second solution and you're good to go with just:

try (Connection con = DriverManager.getConnection(connectionUri, userName, password);
     Statement stmt = con.createStatement()) {

    stmt.executeUpdate(query);

} catch (SQLException e) {
    e.printStackTrace();
}

* Which is the case for version 1.2.0 or newer of the Hive JDBC driver

Upvotes: 2

Jörn Buitink
Jörn Buitink

Reputation: 2916

The idea behind try-with-ressource is to close an AutoCloseable class. So every usage of a class which should be closed after using it (a Ressource) can be used with try-with-ressource (like Connection for example). You don't have to take care of closing it manually (in an finally block for example).

So yes, your idea is right:

  • try/catch for Class.forName("org.apache.hive.jdbc.HiveDriver"); - because this is not AutoCloseable
  • try-with-ressource for Connection con = DriverManager.getConnection(connectionUri, userName, password); Statement stmt = con.createStatement();- because Connection and Statement implement AutoCloseable

Reference: https://docs.oracle.com/javase/7/docs/api/java/lang/AutoCloseable.html

Upvotes: 6

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