CODEWITHSUNDEEP
sqljdbcexecute
Welite
Welite

Reputation: 153

Java closing Statement

I am not sure, which method is better?

con.createStatement().execute("...");

OR

Statement st = con.createStatement();
st.execute("...");
st.close();

When using the first method, will be the statement create closed or it will remain open? I am sure that in the second method the statement will be closed, but in the first one? Anybody know?

Upvotes: 1

Views: 2860

Answers (4)

Mark Rotteveel
Mark Rotteveel

Reputation: 108971

Neither is good, although the second alternative is better than the first. You should always close a statement when you are done with (not sooner, but definitely not never). Your second alternative attempts to close the statement, but will actually fail to do that if execute throws an exception.

To have a guaranteed close of your statement, you can use try-with-resource (introduced in Java 7):

try (Statement statement = connection.createStatement) {
    statement.execute();
    // Other things you want to with statement...
}

If you are unfortunate to be stuck on Java 6 or earlier, you need to use a try/finally:

Statement statement = connection.createStatement();
try {
    statement.execute();
    // Other things you want to with statement...
} finally {
    statement.close();
}

Upvotes: 2

Channa Jayamuni
Channa Jayamuni

Reputation: 1905

Both con.createStatement().execute("..."); and Statement st = con.createStatement(); make same sense. However closing the statement is not performed with the first method. Closing the ResultSet or Statement is a good practice. You may get additional problems with not closed Statements. You can close the Connection instead, but it's not possible when using a connection pool. Additionally the second method is very useful when using the PrepairedStatement, because it can set parameters to the PreparedStatement.

Upvotes: 0

John Bollinger
John Bollinger

Reputation: 180161

If you do not explicitly close the Statement object then it will remain open, at least initially. It might be closed some time after the garbage collector determines that it is unreachable, if ever that happens. It will be closed when the connection is closed, if at that time it is still open.

The best form is usually:

Statement st = con.createStatement();

try {
    // ...
    st.execute("...");
    // ...
} finally {
    st.close();
}

By starting a try block immediately after creating a statement, you can be sure that the statement will be closed (in the finally block) before it goes out of scope -- even if an arbitrary exception is thrown somewhere within.

Upvotes: 1

Mureinik
Mureinik

Reputation: 311188

In the first snippets, you are not explicitly closing the statement, so you can not rely on it being closed. Some driver's implementations call close() in the statement's finalize() method, but you should not rely on this, and should always explicitly close your statements.

Upvotes: 0

Related Questions