ImmutableCollectors.java 文件源码

public static <T, K, V> Collector<T, ?, ImmutableSortedMap<K, V>> toSortedMap(Comparator<? super K> comparator, Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends V> valueMapper) {
    return Collector.of(
            () -> new ImmutableSortedMap.Builder<K, V>(comparator),
            (builder, input) -> builder.put(keyMapper.apply(input), valueMapper.apply(input)),
            (l, r) -> l.putAll(r.build()),
            ImmutableSortedMap.Builder::build,
            Collector.Characteristics.UNORDERED
    );
}