Java 8 Stream Collectors that should have been in the JDK from the start!

MoreCollectors.java

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collector;

import static java.util.function.Function.identity;
import static java.util.stream.Collectors.toMap;

/**
 * Just some stuff that the JDK is missing :rolleyes:
 */
public class MoreCollectors {

    /**
     * Collect a stream into a LinkedHashMap using the identity function
     */
    public static <T> Collector<T, ?, Map<T, T>> toLinkedMap() {
        return toLinkedMap(identity(), identity());
    }

    /**
     * Collect a stream into a LinkedHashMap, using the specified mappers
     */
    public static <T, K, U> Collector<T, ?, Map<K, U>> toLinkedMap(
            Function<? super T, ? extends K> keyMapper,
            Function<? super T, ? extends U> valueMapper) {
        return toMap(keyMapper, valueMapper,
                (o, o2) -> {
                    throw new IllegalStateException(String.format("Duplicate key %s", o));
                },
                LinkedHashMap::new);
    }
}