closeOnCompletion在MySQL JDBC 5.1.32中无法正常工作

Question

I have a snippet like this:

Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery("SELECT * FROM table_A");

statement.closeOnCompletion();
System.out.println(statement.isCloseOnCompletion());

rs.close();
System.out.println(statement.isClosed());

After closeOnCompletion is invoked, I expect the statement to be closed, as its result set is closed. However, it just shows "false" when checking statement.isClosed().

Did I misunderstand the jdk doc? as it says: closeOnCompletion() Specifies that this Statement will be closed when all its dependent result sets are closed.

=========================== Update: It turns out to be my carelessness. The last statement actually returns a result of expected "true". So it's no longer an issue

Answer 1

Since Statement is depend on result I would suggest this

Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery("SELECT * FROM table_A");

rs.close();
statement.close();  
System.out.println(statement.isClosed());

This is applicable if your ultimate want is to close statement, if your question is why statement is not closing even when called onexit, then better to refer javadocs.