java TextField 中的 RequestFocus 不起作用
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RequestFocus in TextField doesn't work
提问by Adil
I use JavaFX 2.1 and I created GUI using FXML, in the controller of this GUI I added myTextField.requestFocus();.
我使用 JavaFX 2.1 并使用 FXML 创建了 GUI，在我添加的这个 GUI 的控制器中myTextField.requestFocus();。
But I always get the focus in the other control.
但我总是把焦点放在另一个控件上。
回答by Sergey Grinev
At the time of initialize()controls are not yet ready to handle focus.
在initialize()控件还没有准备好处理焦点的时候。
You can try next trick:
您可以尝试下一个技巧：
@Override
public void initialize(URL url, ResourceBundle rb) {
Platform.runLater(new Runnable() {
@Override
public void run() {
tf.requestFocus();
}
});
}
For tricky complex applications (like Pavel_K has in the comments) you may want to repeat this routine several times and call method line next one:
对于棘手的复杂应用程序（如 Pavel_K 在注释中的应用），您可能需要多次重复此例程并调用下一行的方法：
private void repeatFocus(Node node) {
Platform.runLater(() -> {
if (!node.isFocused()) {
node.requestFocus();
repeatFocus(node);
}
});
}
Note this is undocumented approach and it may be wise to add a limit for repetitions to avoid endless loop if something changed or broke in future Java releases. Better to lose focus than a whole app. :)
请注意，这是未记录的方法，如果在未来的 Java 版本中发生更改或损坏，则添加重复限制以避免无限循环可能是明智的。比整个应用程序更好地失去焦点。:)
回答by Sedrick
The exact same answer as @Sergey Grinev. Make sure your version of java is up-to-date (JDK 1.8 or later).
与@Sergey Grinev 完全相同的答案。确保您的 java 版本是最新的（JDK 1.8 或更高版本）。
Platform.runLater(()->myTextField.requestFocus());
回答by codepleb
If you requestFocus(); AFTER initializing the scene, it will work!
如果你 requestFocus(); 初始化场景后，它将起作用！
Like this:
像这样：
Stage stage = new Stage();
GridPane grid = new GridPane();
//... add buttons&stuff to pane
Scene scene = new Scene(grid, 800, 600);
TEXTFIELD.requestFocus();
stage.setScene(scene);
stage.show();
I hope this helps. :)
我希望这有帮助。:)
回答by nickthecoder
This can occur when the Scene property for the Node is not yet set. Alas, the scene property can take a "long" time to be set.
当节点的 Scene 属性尚未设置时，可能会发生这种情况。唉，场景属性可能需要“很长时间”才能设置。
The child node's scene property lags when a scene is first created, and also, when items are added to some parents, such as a TabPane (oddly some parents seem immune, I'm not sure why).
子节点的场景属性在首次创建场景时滞后，并且当项目添加到某些父节点时，例如 TabPane（奇怪的是有些父节点似乎免疫，我不知道为什么）。
The correct strategy, which has always worked for me :
正确的策略，它一直对我有用：
if (myNode.scene) == null {
// listen for the changes to the node's scene property,
// and request focus when it is set
} else {
myNode.requestFocus()
}
I have a handy Kotlin extension function which does this.
我有一个方便的 Kotlin 扩展函数可以做到这一点。
fun Node.requestFocusOnSceneAvailable() {
if (scene == null) {
val listener = object : ChangeListener<Scene> {
override fun changed(observable: ObservableValue<out Scene>?, oldValue: Scene?, newValue: Scene?) {
if (newValue != null) {
sceneProperty().removeListener(this)
requestFocus()
}
}
}
sceneProperty().addListener(listener)
} else {
requestFocus()
}
}
You can then call it from within you code like so :
然后，您可以从代码中调用它，如下所示：
myNode.requestFocusOnSceneAvailable()
Perhaps somebody would like to translate it to Java.
也许有人想把它翻译成Java。
