Get Number of Rows returned by ResultSet in Java

Another way to differentiate between 0 rows or some rows from a ResultSet:

ResultSet res = getData();

if(!res.isBeforeFirst()){          //res.isBeforeFirst() is true if the cursor
                                   //is before the first row.  If res contains
                                   //no rows, rs.isBeforeFirst() is false.

    System.out.println("0 rows");
}
else{
    while(res.next()){
        // code to display the rows in the table.
    }
}

If you must know the number of rows given a ResultSet, here is a method to get it:

public int getRows(ResultSet res){
    int totalRows = 0;
    try {
        res.last();
        totalRows = res.getRow();
        res.beforeFirst();
    } 
    catch(Exception ex)  {
        return 0;
    }
    return totalRows ;    
}

First, you should create Statement which can be move cursor by command:

Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);

Then retrieve the ResultSet as below:

ResultSet rs = stmt.executeQuery(...);

Move cursor to the latest row and get it:

if (rs.last()) {
    int rows = rs.getRow();
    // Move to beginning
    rs.beforeFirst();
    ...
}

Then rows variable will contains number of rows returned by sql

You could use a do ... while loop instead of a while loop, so that rs.next() is called after the loop is executed, like this:

if (!rs.next()) {                            //if rs.next() returns false
                                             //then there are no rows.
    System.out.println("No records found");

}
else {
    do {
        // Get data from the current row and use it
    } while (rs.next());
}

Or count the rows yourself as you're getting them:

int count = 0;

while (rs.next()) {
    ++count;
    // Get data from the current row and use it
}

if (count == 0) {
    System.out.println("No records found");
}

A simple getRowCount method can look like this :

private int getRowCount(ResultSet resultSet) {
    if (resultSet == null) {
        return 0;
    }

    try {
        resultSet.last();
        return resultSet.getRow();
    } catch (SQLException exp) {
        exp.printStackTrace();
    } finally {
        try {
            resultSet.beforeFirst();
        } catch (SQLException exp) {
            exp.printStackTrace();
        }
    }

    return 0;
}

Just to be aware that this method will need a scroll sensitive resultSet, so while creating the connection you have to specify the scroll option. Default is FORWARD and using this method will throw you exception.