JavaFX Tooltip

快来打我* 2023-10-15 14:22 55阅读 0赞

The *JavaFX Tooltip* class (`javafx.scene.control.Tooltip`) can display a small popup with explanatory text when the user hovers the mouse over a JavaFX control. A `Tooltip` is a well-known feature of modern desktop and web GUIs. A Tooltip is useful to provide extra help text in GUIs where there is not space enough available to have an explanatory text visible all the time, e.g. in the button text.

### Creating a Tooltip Instance ###

To use the JavaFX `Tooltip` class you must create a `Tooltip` instance. Here is an example of creating a JavaFX `Tooltip` instance:

Tooltip tooltip1 = new Tooltip("Creates a new file");

The text passed as parameter to the `Tooltip` constructor is the text displayed when the `Tooltip` is visible.

### Adding a Tooltip to a JavaFX Component ###

Once you have created a `Tooltip` instance you need to add it to a JavaFX component to make it active. Here is an example of adding a `Tooltip` instance to a JavaFX Button:

Tooltip tooltip1 = new Tooltip("Creates a new file");
    
    Button button1 = new Button("New");
    button1.setTooltip(tooltip1);

Notice the call to `Button`'s `setTooltip()` method. This is what causes the `Tooltip` instance to be visible when the mouse is hovered over the button.

Here is a screenshot showing how the resulting `Tooltip` could look:

![8639030d02514cb98b911380b69b7069.png][]

### Text Alignment ###

You can set the text alignment of the text inside the `Tooltip` box via its `setTextAlignment()` method. Here is an example of setting the text alignment of a `Tooltip`:

tooltip1.setTextAlignment(TextAlignment.LEFT);

The class `javafx.scene.text.TextAlignment` contains four different constants that represent different kinds of text alignment. The four constants are:

*  `LEFT`
 *  `RIGHT`
 *  `CENTER`
 *  `JUSTIFY`

The first three constants represents the left, right and center justification of text within the popup box. The last constant, `JUSTIFY`, will align the text with both the left and right edges of the popup box by increasing the space in between the words to make the text fit.

Notice that setting the text alignment may not result in a visible effect on the text alignment. That is because by default width of the popup box around the text is calculated based on the width of the text. If your text is just a single line, the text will almost always appear centered within the popup box. Text alignment first really takes effect when the popup box contains multiple lines of text, or if you set the width of the `Tooltip` explicitly (manually).

### Tooltip Graphics ###

You can set a graphic icon for a `Tooltip` via the `setGraphic()` method. Here is an example of setting a graphic icon for a `Tooltip` :

tooltip1.setGraphic(new ImageView("file:iconmonstr-basketball-1-16.png"));

Here is an example screenshot illustrating how a `Tooltip` graphic could look:

![392f0c92fde340bb94b538f6b5325590.png][]

[8639030d02514cb98b911380b69b7069.png]: https://img-blog.csdnimg.cn/8639030d02514cb98b911380b69b7069.png
[392f0c92fde340bb94b538f6b5325590.png]: https://img-blog.csdnimg.cn/392f0c92fde340bb94b538f6b5325590.png