Data Access with Lambdas - Java Closures and Lambda - page 88

*/
public abstract class ResultSetIterator<RESULT_T>
implements Iterator<RESULT_T>
{
private final ResultSet resultSet;
private final AutoCloseable[] toClose;
private volatile Boolean hasNext = null;
/**
* Constructor.
*
* @param resultSet The result set to process; may not be {@code null}.
* @param toClose Optional additional autocloseables (such as
* {@link java.sql.Connection}) to close
* when the result set is exhausted; may be {@code null}
* (equivalent to empty).
*/
public ResultSetIterator(final ResultSet resultSet, final AutoCloseable... toClose) {
Objects.requireNonNull(resultSet, "result set");
this.resultSet = resultSet;
if (toClose == null) {
this.toClose = new AutoCloseable[0];
} else {
this.toClose = toClose;
}
}
/**
* Given a {@link java.sql.ResultSet} instance on a current row,
* return a {@code RESULT_T} instance for that row.
* This code should not call {@link java.sql.ResultSet#next()} or
* otherwise mutate the result set: it should
* be treated as read-only.
*
* @param resultSet The result set to load.
* @return The result instance.
* @throws java.sql.SQLException If an error occurs.
*/
protected abstract RESULT_T processRow(ResultSet resultSet)
throws SQLException;
private void doClose() {
try {
if (!resultSet.isClosed()) resultSet.close();
} catch (SQLException ignore) {}
for (int i = 0; i < toClose.length; i++) {
try {
AutoCloseable closeMe = toClose[i];
toClose[i] = null;
if (closeMe != null && closeMe != resultSet) closeMe.close();