src/main/java/io/reactivex/Flowable.java
@CheckReturnValue
    @NonNull
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <T> Flowable<T> just(T item) {
        ObjectHelper.requireNonNull(item, "item is null");
        return RxJavaPlugins.onAssembly(new FlowableJust<T>(item));
    }
@CheckReturnValue
    @NonNull
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <T> Flowable<T> just(T item) {
        ObjectHelper.requireNonNull(item, "item is null");
        return RxJavaPlugins.onAssembly(new FlowableJust<T>(item));
    }
@ CheckReturnValue @ NonNull @ BackpressureSupport ( BackpressureKind . FULL ) @ SchedulerSupport ( SchedulerSupport . NONE ) public static < T > Flowable < T > just ( T item ) { ObjectHelper . requireNonNull ( item , "item is null" ) ; return RxJavaPlugins . onAssembly ( new FlowableJust < T > ( item ) ) ; }
Returns a Flowable that signals the given (constant reference) item and then completes.
<p>
<img width="640" height="310" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/just.png" alt="">
<p>
Note that the item is taken and re-emitted as is and not computed by any means by {@code just}. Use {@link #fromCallable(Callable)}
to generate a single item on demand (when {@code Subscriber}s subscribe to it).
<p>
See the multi-parameter overloads of {@code just} to emit more than one (constant reference) items one after the other.
Use {@link #fromArray(Object...)} to emit an arbitrary number of items that are known upfront.
<p>
To emit the items of an {@link Iterable} sequence (such as a {@link java.util.List}), use {@link #fromIterable(Iterable)}.
<dl>
<dt><b>Backpressure:</b></dt>
<dd>The operator honors backpressure from downstream.</dd>
<dt><b>Scheduler:</b></dt>
<dd>{@code just} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param item
the item to emit
@param <T>
the type of that item
@return a Flowable that emits {@code value} as a single item and then completes
@see <a href="http://reactivex.io/documentation/operators/just.html">ReactiveX operators documentation: Just</a>
@see #just(Object, Object)
@see #fromCallable(Callable)
@see #fromArray(Object...)
@see #fromIterable(Iterable)
Returns a Flowable that signals the given ( constant reference ) item and then completes . <p > <img width = 640 height = 310 src = https : // raw . github . com / wiki / ReactiveX / RxJava / images / rx - operators / just . png alt = > <p > Note that the item is taken and re - emitted as is and not computed by any means by { @code just } . Use { @link #fromCallable ( Callable ) } to generate a single item on demand ( when { @code Subscriber } s subscribe to it ) . <p > See the multi - parameter overloads of { @code just } to emit more than one ( constant reference ) items one after the other . Use { @link #fromArray ( Object ... ) } to emit an arbitrary number of items that are known upfront . <p > To emit the items of an { @link Iterable } sequence ( such as a { @link java . util . List } ) use { @link #fromIterable ( Iterable ) } . <dl > <dt > <b > Backpressure : < / b > < / dt > <dd > The operator honors backpressure from downstream . < / dd > <dt > <b > Scheduler : < / b > < / dt > <dd > { @code just } does not operate by default on a particular { @link Scheduler } . < / dd > < / dl >