Java ResultSet how to check if there are any results

Resultset has no method for hasNext. I want to check if the resultSet has any value

is this the correct way

if (!resultSet.next() ) {
    System.out.println("no data");
} 

Solution 1:

Assuming you are working with a newly returned ResultSet whose cursor is pointing before the first row, an easier way to check this is to just call isBeforeFirst(). This avoids having to back-track if the data is to be read.

As explained in the documentation, this returns false if the cursor is not before the first record or if there are no rows in the ResultSet.

if (!resultSet.isBeforeFirst() ) {    
    System.out.println("No data"); 
} 

Solution 2:

That's correct, initially the ResultSet's cursor is pointing to before the first row, if the first call to next() returns false then there was no data in the ResultSet.

If you use this method, you may have to call beforeFirst() immediately after to reset it, since it has positioned itself past the first row now.

It should be noted however, that Seifer's answer below is a more elegant solution to this question.

Solution 3:

you could always do the next up front, and just do a post loop check

if (!resultSet.next() ) {
    System.out.println("no data");
} else {

    do {
     //statement(s)
    } while (resultSet.next());
}

Solution 4:

To be totally sure of rather the resultset is empty or not regardless of cursor position, I would do something like this:

public static boolean isMyResultSetEmpty(ResultSet rs) throws SQLException {
    return (!rs.isBeforeFirst() && rs.getRow() == 0);
}

This function will return true if ResultSet is empty, false if not or throw an SQLException if that ResultSet is closed/uninitialized.

Solution 5:

You would usually do something like this:

while ( resultSet.next() ) { 
   // Read the next item
   resultSet.getString("columnName");
}

If you want to report an empty set, add a variable counting the items read. If you only need to read a single item, then your code is adequate.