how is close() used?

[Stephan Ort]

hi i'm wondering how the close() method is used exactly.

which one is correct, when you want to make two queries?:

1)

Statement stat = connection.createStatement();
ResultSet rs = stat.executeQuery(/*a query*/);
/*use rs*/
stat.close();
rs.close();
rs = stat.executeQuery(/*another query*/);
/*use rs*/
stat.close();
rs.close();

2)

Statement stat = connection.createStatement();
ResultSet rs = stat.executeQuery(/*a query*/);
/*use rs*/
rs = stat.executeQuery(/*another query*/);
/*use rs*/
stat.close();
rs.close();

3)

Statement stat = connection.createStatement();
ResultSet rs = stat.executeQuery(/*a query*/);
/*use rs*/
stat.close();
rs.close();
Statement stat2 = connection.createStatement();
ResultSet rs2 = stat2.executeQuery(/*another query*/);
/*use rs2*/
stat2.close();
rs2.close();

which of these make all of the possible closings, or does none?

are there easier ways to use one Statement objects for more than one query although all possible closings are done? Is this even possible?

[Jeanne Boyarsky]

None. You should be closing the result set before the statement.

[Stephan Ort]

thanks, so it would be:

Statement stat = connection.createStatement();  
ResultSet rs = stat.executeQuery(/*a query*/);  
/*use rs*/ 
rs.close();  
rs = stat.executeQuery(/*another query*/);  
/*use rs*/  
stat.close();  
rs.close();  

[Jan Cumps]

No. Now you are closing the resultset before you finished using it.
Jeanne was saying that you should close the resultset before closing the statement.

We advise you to close the jdbc resources in a finally block.

[Vijayakumar Rengaraj]

In between the two DB interactions you can close the resultset but not the statement object .

But it is not advisable to close the resultset and statement objects within try block.
you can try the below code:

finally{
if(rs!=null)
rs.close();
if(stmt!=null)
stmt.close();
}

[Lalit Mehra]

you should close the resultset before closing the statement object relating it.

must make sure that you are done manipulating the resultset before closing it.

[Jan Cumps]

Welcome to JavaRanch, Vijayakumar!