匿名内部类和lambda表达式
new Thread(new Runnable() {
@Override
public void run() {
System.out.println(Thread.currentThread().getName());
}
});
new Thread(() -> {
System.out.println(Thread.currentThread().getName());
}).start();
函数式接口
@FunctionalInterface
只允许有一个抽象方法，例如Runable和Callable接口。
@FunctionalInterface
public interface Runnable {
public abstract void run();
}
@FunctionalInterface
public interface Callable<V> {
V call() throws Exception;
}
继承关系如图所示
public interface AutoCloseable {
void close() throws Exception;
}
public interface BaseStream<T, S extends BaseStream<T, S>>
extends AutoCloseable {
Iterator<T> iterator();
Spliterator<T> spliterator();
boolean isParallel();
S sequential();
S parallel();
S unordered();
S onClose(Runnable closeHandler);
@Override
void close();
}
public interface Stream<T> extends BaseStream<T, Stream<T>> {
Stream<T> filter(Predicate<? super T> predicate);
<R> Stream<R> map(Function<? super T, ? extends R> mapper);
IntStream mapToInt(ToIntFunction<? super T> mapper);
LongStream mapToLong(ToLongFunction<? super T> mapper);
DoubleStream mapToDouble(ToDoubleFunction<? super T> mapper);
<R> Stream<R> flatMap(Function<? super T, ? extends Stream<? extends R>> mapper);
IntStream flatMapToInt(Function<? super T, ? extends IntStream> mapper);
LongStream flatMapToLong(Function<? super T, ? extends LongStream> mapper);
DoubleStream flatMapToDouble(Function<? super T, ? extends DoubleStream> mapper);
Stream<T> distinct();
Stream<T> sorted();
Stream<T> sorted(Comparator<? super T> comparator);
Stream<T> peek(Consumer<? super T> action);
Stream<T> limit(long maxSize);
Stream<T> skip(long n);
void forEach(Consumer<? super T> action);
void forEachOrdered(Consumer<? super T> action);
Object[] toArray();
<A> A[] toArray(IntFunction<A[]> generator);
T reduce(T identity, BinaryOperator<T> accumulator);
Optional<T> reduce(BinaryOperator<T> accumulator);
<U> U reduce(U identity,
BiFunction<U, ? super T, U> accumulator,
BinaryOperator<U> combiner);
<R> R collect(Supplier<R> supplier,
BiConsumer<R, ? super T> accumulator,
BiConsumer<R, R> combiner);
<R, A> R collect(Collector<? super T, A, R> collector);
Optional<T> min(Comparator<? super T> comparator);
Optional<T> max(Comparator<? super T> comparator);
long count();
boolean anyMatch(Predicate<? super T> predicate);
boolean allMatch(Predicate<? super T> predicate);
boolean noneMatch(Predicate<? super T> predicate);
Optional<T> findFirst();
Optional<T> findAny();
public static<T> Builder<T> builder() {
return new Streams.StreamBuilderImpl<>();
}
public static<T> Stream<T> empty() {
return StreamSupport.stream(Spliterators.<T>emptySpliterator(), false);
}
public static<T> Stream<T> of(T t) {
return StreamSupport.stream(new Streams.StreamBuilderImpl<>(t), false);
}
@SafeVarargs
@SuppressWarnings("varargs") // Creating a stream from an array is safe
public static<T> Stream<T> of(T... values) {
return Arrays.stream(values);
}
public static<T> Stream<T> iterate(final T seed, final UnaryOperator<T> f) {
Objects.requireNonNull(f);
final Iterator<T> iterator = new Iterator<T>() {
@SuppressWarnings("unchecked")
T t = (T) Streams.NONE;
@Override
public boolean hasNext() {
return true;
}
@Override
public T next() {
return t = (t == Streams.NONE) ? seed : f.apply(t);
}
};
return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
iterator,
Spliterator.ORDERED | Spliterator.IMMUTABLE), false);
}
public static <T> Stream<T> concat(Stream<? extends T> a, Stream<? extends T> b) {
Objects.requireNonNull(a);
Objects.requireNonNull(b);
@SuppressWarnings("unchecked")
Spliterator<T> split = new Streams.ConcatSpliterator.OfRef<>(
(Spliterator<T>) a.spliterator(), (Spliterator<T>) b.spliterator());
Stream<T> stream = StreamSupport.stream(split, a.isParallel() || b.isParallel());
return stream.onClose(Streams.composedClose(a, b));
}
public interface Builder<T> extends Consumer<T> {
@Override
void accept(T t);
default Builder<T> add(T t) {
accept(t);
return this;
}
Stream<T> build();
}
}
Stream接口中有内部接口Builder，其继承关系如图所示
注解FunctionalInterface，作用用于标识函数式接口
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface FunctionalInterface {}
Consumer接口是一个函数式接口，
@FunctionalInterface
public interface Consumer<T> {
void accept(T t);
default Consumer<T> andThen(Consumer<? super T> after) {
Objects.requireNonNull(after);
return (T t) -> { accept(t); after.accept(t); };
}
}
Builder接口
public interface Builder<T> extends Consumer<T> {
@Override
void accept(T t);
default Builder<T> add(T t) {
accept(t);
return this;
}
Stream<T> build();
}
