Rxjava(创建类)--Never

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Never

创建一个不发射数据也不终止的Observable

        Observable.<String>never().subscribe(new Observer<String>() {            @Override            public void onNext(String s) {                log("onNext:" + s);            }            @Override            public void onCompleted() {                log("onCompleted");            }            @Override            public void onError(Throwable e) {                log("onError:" + e.getMessage());            }        });

可以看到哪个on*函数都没有执行

我们看下never函数

  public static <T> Observable<T> never() {        return NeverObservableHolder.instance();    }

public enum NeverObservableHolder implements OnSubscribe<Object> {    INSTANCE    ;    /** The singleton instance. */    static final Observable<Object> NEVER = Observable.create(INSTANCE);    /**     * Returns a type-corrected singleton instance of the never Observable.     * @param <T> the value type     * @return a type-corrected singleton instance of the never Observable.     */    @SuppressWarnings("unchecked")    public static <T> Observable<T> instance() {        return (Observable<T>)NEVER;    }    @Override    public void call(Subscriber<? super Object> child) {        // deliberately no op    }}

call函数什么也没做

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