JDBC & Stream API

package ch.claude_martin;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

class SomeClass {
    public static void main(String[] args) throws Throwable {
        Connection conn = null;
        PreparedStatement stmt = conn.prepareStatement("SELECT * FROM FOO", ResultSet.TYPE_SCROLL_INSENSITIVE,
                ResultSet.CONCUR_READ_ONLY);
        ResultSet rs = stmt.executeQuery();
        long size;
        try {
            rs.last();
            size = rs.getRow();
            rs.beforeFirst();
        } catch (Exception ex) {
            size = Long.MAX_VALUE;
        }
        Stream<Foo> stream = StreamSupport.stream(new AbstractSpliteratorExtension(rs, size), false);

        var result = stream.map(mapper1).map(mapper2).filter(someFilter).collect(myCollector);
    }

    private static final class AbstractSpliteratorExtension extends Spliterators.AbstractSpliterator<Foo> {
        private final ResultSet rs;

        private AbstractSpliteratorExtension(ResultSet rs, long size) {
            super(size, Spliterator.ORDERED);
            this.rs = rs;
        }

        @Override
        public boolean tryAdvance(Consumer<? super Foo> action) {
            try {
                if (!rs.next())
                    return false;
                action.accept(Foo.of(rs));
                return true;
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public static class Foo {
        public static Foo of(ResultSet rs) { ... }
    }
}