Question

I want to get the size of the ResultSet inside the while loop.

Tried the code below, and I got the results that I want. But it seems to be messing up with result.next() and the while loop only loops once if I do this.
What’s the proper way of doing this?

result.first();
while (result.next()){

    System.out.println(result.getString(2));
    System.out.println("A. " + result.getString(5) + "\n" + "B. " + result.getString(6) + "\n" + "C. " + result.getString(7) + "\n" + "D. " + result.getString(8));
    System.out.println("Answer: ");
    answer = inputquiz.next();

    result.last();

    if (answer.equals(result.getString(10))) {
        score++;
        System.out.println(score + "/" + result.getRow());
    } else {
        System.out.println(score + "/" + result.getRow());
    }
}

Answer 1

What’s the proper way of doing this?

Map it to a List<Entity>. Since your code is far from self-documenting (you’re using indexes instead of column names), I can’t give a well suited example. So I’ll take a Person as example.

First create a javabean class representing whatever a single row contains.

public class Person {
    private Long id;
    private String firstName;
    private String lastName;
    private Date dateOfBirth;

    // Add/generate c'tors/getters/setters/equals/hashcode and other boilerplate.
}

(a bit decent IDE like Eclipse can autogenerate them)

Then let JDBC do the following job.

List<Person> persons = new ArrayList<Person>();

while (resultSet.next()) {
    Person person = new Person();
    person.setId(resultSet.getLong("id"));
    person.setFirstName(resultSet.getString("fistName"));
    person.setLastName(resultSet.getString("lastName"));
    person.setDataOfBirth(resultSet.getDate("dateOfBirth"));
    persons.add(person);
}

// Close resultSet/statement/connection in finally block.

return persons;

Then you can just do

int size = persons.size();

And then to substitute your code example

for (int i = 0; i < persons.size(); i++) {
    Person person = persons.get(i);
    System.out.println(person.getFirstName());
    int size = persons.size(); // Do with it whatever you want.
}

See also:

• How to check if there is zero-or-one result or one-or-more results and their size