How to get the size of a java.sql.ResultSet?
Solution 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:
Solution 2
This is a tricky question.
Normally,
result.last()
scrolls to the end of theResultSet
, and you can't go back.If you created the statement using one of the
createStatement
orprepareStatement
methods with a "resultSetType" parameter, and you've set the parameter toResultSet.TYPE_SCROLL_INSENSITIVE
orResultSet.TYPE_SCROLL_SENSITIVE
, then you can scroll theResultSet
usingfirst()
orrelative()
or some other methods.
However, I'm not sure if all databases / JDBC drivers support scrollable result sets, and there are likely to be performance implications in doing this. (A scrollable result set implies that either the database or the JVM needs to buffer the entire resultset somewhere ... or recalculate it ... and that's expensive for a large resultset.)
Solution 3
you could do result.last();
and call result.getRow();
(which retrieves the current row number) to get count. but it'll have load the all the rows and if it's a big result set, it might not be very efficient. The best way to go about is to do a SELECT COUNT(*)
on you query and get the count like it's demonstrated in this post, beforehand.
Solution 4
The way of getting size of ResultSet, No need of using ArrayList etc
int size =0;
if (rs != null)
{
rs.beforeFirst();
rs.last();
size = rs.getRow();
}
Now You will get size, And if you want print the ResultSet, before printing use following line of code too,
rs.beforeFirst();
user225269
Updated on November 20, 2022Comments
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user225269 over 1 year
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()); } }
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blo0p3r about 10 yearspossible duplicate of How do I get the size of a java.sql.ResultSet?
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