package io.ebean;
import java.util.Iterator;
/**
* Used to provide iteration over query results.
* <p>
* This can be used when you want to process a very large number of results and
* means that you don't have to hold all the results in memory at once (unlike
* findList(), findSet() etc where all the beans are held in the List or Set
* etc).
* </p>
* <p>
* Note that findIterate (and findEach and findEachWhile) uses a "per graph"
* persistence context scope and adjusts jdbc fetch buffer size for large
* queries. As such it is better to use findList for small queries.
* </p>
* <p>
* Remember that with {@link QueryIterator} you must call {@link QueryIterator#close()}
* when you have finished iterating the results. Use "try with resources" or ensure it
* is closed in a finally block.
* </p>
* <h3>Try finally style</h3>
* <pre>{@code
*
* Query<Customer> query = server.find(Customer.class)
* .where().gt("id", 0)
* .orderBy("id")
* .setMaxRows(2);
*
* QueryIterator<Customer> it = query.findIterate();
* try {
* while (it.hasNext()) {
* Customer customer = it.next();
* // do something with customer ...
* }
* } finally {
* // close the underlying resources
* it.close();
* }
*
* }</pre>
* <p>
* <h3>Try with resources style</h3>
* <pre>{@code
*
* // try with resources
* try (QueryIterator<Customer> it = query.findIterate()) {
* while (it.hasNext()) {
* Customer customer = it.next();
* // do something with customer ...
* }
* }
*
* }</pre>
*
* @param <T> the type of entity bean in the iteration
*/
public interface QueryIterator<T> extends Iterator<T>, java.io.Closeable {
/**
* Returns <tt>true</tt> if the iteration has more elements.
*/
@Override
boolean hasNext();
/**
* Returns the next element in the iteration.
*/
@Override
T next();
/**
* Remove is not allowed.
*/
@Override
void remove();
/**
* Close the underlying resources held by this iterator.
*/
@Override
void close();
}