> For the complete documentation index, see [llms.txt](https://3440217568.gitbook.io/rxswift/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://3440217568.gitbook.io/rxswift/decision_tree/just.md).

# just

**创建 `Observable` 发出唯一的一个元素**

![](https://4217506537-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MWj545abP2yK86-qksJ%2Fsync%2F57c6129d2c40f3ffad29b800ba2d5c27ac9e518d.png?generation=1616819384752922\&alt=media)

**just** 操作符将某一个元素转换为 `Observable`。

## 演示

一个序列只有唯一的元素 **0**：

```swift
let id = Observable.just(0)
```

它相当于：

```swift
let id = Observable<Int>.create { observer in
    observer.onNext(0)
    observer.onCompleted()
    return Disposables.create()
}
```