public class Optional<T> extends java.lang.Object
描述：为了使Rxjava2 onNext 返回null,使用了此包装类，进行过渡
Optional(<any> obs)
T
get()
static <T> Optional<T>
of(T value)
ofNullable(T value)
orElse(T defaultValue)
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public Optional(<any> obs)
public static <T> Optional<T> of(T value)
public static <T> Optional<T> ofNullable(T value)
public T get()
public T orElse(T defaultValue)