[java] How can I avoid ResultSet is closed exception in Java?

As soon as my code gets to my while(rs.next()) loop it produces the ResultSet is closed exception. What causes this exception and how can I correct for it?

EDIT: I notice in my code that I am nesting while(rs.next()) loop with another (rs2.next()), both result sets coming from the same DB, is this an issue?

The exception states that your result is closed. You should examine your code and look for all location where you issue a ResultSet.close() call. Also look for Statement.close() and Connection.close(). For sure, one of them gets called before rs.next() is called.

make sure you have closed all your statments and resultsets before running rs.next. Finaly guarantees this

public boolean flowExists( Integer idStatusPrevious, Integer idStatus, Connection connection ) {
    LogUtil.logRequestMethod();

    PreparedStatement ps = null;
    ResultSet rs = null;
    try {
        ps = connection.prepareStatement( Constants.SCRIPT_SELECT_FIND_FLOW_STATUS_BY_STATUS );
        ps.setInt( 1, idStatusPrevious );
        ps.setInt( 2, idStatus );

        rs = ps.executeQuery();

        Long count = 0L;

        if ( rs != null ) {
            while ( rs.next() ) {
                count = rs.getLong( 1 );
                break;
            }
        }

        LogUtil.logSuccessMethod();

        return count > 0L;
    } catch ( Exception e ) {
        String errorMsg = String
            .format( Constants.ERROR_FINALIZED_METHOD, ( e.getMessage() != null ? e.getMessage() : "" ) );
        LogUtil.logError( errorMsg, e );

        throw new FatalException( errorMsg );
    } finally {
        rs.close();
        ps.close();
    }

This could be caused by a number of reasons, including the driver you are using.

a) Some drivers do not allow nested statements. Depending if your driver supports JDBC 3.0 you should check the third parameter when creating the Statement object. For instance, I had the same problem with the JayBird driver to Firebird, but the code worked fine with the postgres driver. Then I added the third parameter to the createStatement method call and set it to ResultSet.HOLD_CURSORS_OVER_COMMIT, and the code started working fine for Firebird too.

static void testNestedRS() throws SQLException {

    Connection con =null;
    try {
        // GET A CONNECTION
        con = ConexionDesdeArchivo.obtenerConexion("examen-dest");
        String sql1 = "select * from reportes_clasificacion";

        Statement st1 = con.createStatement(
                ResultSet.TYPE_SCROLL_INSENSITIVE,
                ResultSet.CONCUR_READ_ONLY, 
                ResultSet.HOLD_CURSORS_OVER_COMMIT);
        ResultSet rs1 = null;

        try {
            // EXECUTE THE FIRST QRY
            rs1 = st1.executeQuery(sql1);

            while (rs1.next()) {
                // THIS LINE WILL BE PRINTED JUST ONCE ON
                                    // SOME DRIVERS UNLESS YOU CREATE THE STATEMENT 
                // WITH 3 PARAMETERS USING 
                                    // ResultSet.HOLD_CURSORS_OVER_COMMIT
                System.out.println("ST1 Row #: " + rs1.getRow());

                String sql2 = "select * from reportes";
                Statement st2 = con.createStatement(
                        ResultSet.TYPE_SCROLL_INSENSITIVE,
                        ResultSet.CONCUR_READ_ONLY);

                // EXECUTE THE SECOND QRY.  THIS CLOSES THE FIRST 
                // ResultSet ON SOME DRIVERS WITHOUT USING 
                                    // ResultSet.HOLD_CURSORS_OVER_COMMIT

                st2.executeQuery(sql2);

                st2.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            rs1.close();
            st1.close();
        }

    } catch (SQLException e) {

    } finally {
        con.close();

    }

}

b) There could be a bug in your code. Remember that you cannot reuse the Statement object, once you re-execute a query on the same statement object, all the opened resultsets associated with the statement are closed. Make sure you are not closing the statement.

A ResultSetClosedException could be thrown for two reasons.

1.) You have opened another connection to the database without closing all other connections.

2.) Your ResultSet may be returning no values. So when you try to access data from the ResultSet java will throw a ResultSetClosedException.

I got same error everything was correct only i was using same statement interface object to execute and update the database. After separating i.e. using different objects of statement interface for updating and executing query i resolved this error. i.e. do get rid from this do not use same statement object for both updating and executing the query.

You may have closed either the Connection or Statement that made the ResultSet, which would lead to the ResultSet being closed as well.

Also, you can only have one result set open from each statement. So if you are iterating through two result sets at the same time, make sure they are executed on different statements. Opening a second result set on one statement will implicitly close the first. http://java.sun.com/javase/6/docs/api/java/sql/Statement.html

Check whether you have declared the method where this code is executing as static. If it is static there may be some other thread resetting the ResultSet.

Proper jdbc call should look something like:

try { 
    Connection conn;
    Statement stmt;
    ResultSet rs; 

    try {
        conn = DriverManager.getConnection(myUrl,"",""); 
        stmt = conn.createStatement(); 
        rs = stmt.executeQuery(myQuery); 

        while ( rs.next() ) { 
            // process results
        } 

    } catch (SqlException e) { 
        System.err.println("Got an exception! "); 
        System.err.println(e.getMessage()); 
    } finally {
        // you should release your resources here
        if (rs != null) { 
            rs.close();
        }

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

        if (conn != null) {
            conn.close();
        }
    }
} catch (SqlException e) {
    System.err.println("Got an exception! "); 
    System.err.println(e.getMessage()); 
}

you can close connection (or statement) only after you get result from result set. Safest way is to do it in finally block. However close() could also throe SqlException, hence the other try-catch block.