JavaFX中的TextField类概述

超、凢脫俗 2022-12-06 15:27 317阅读 0赞

The *TextField* class in [JavaFX][] is used to create a control that allows the user to enter in a single line of text. It supports having prompt text (i.e., text that informs the user what the *TextField* is meant to be used for).

[JavaFX中][JavaFX]的*TextField*类用于创建允许用户输入单行文本的控件。 它支持具有提示文本(即，通知用户*TextField*打算用于的文本)。

**Note:** If you need a multi-line text input control then have a look at the *TextArea* class. Alternatively, if you want the text to be formatted then have a look at the *HTMLEditor* class.

**注意：**如果需要多行文本输入控件，请查看*TextArea*类。 另外，如果要格式化文本，请查看*HTMLEditor*类。

## 进口声明 **(** Import Statement **)** ##

import javafx.scene.control.TextField;

## 建设者 **(** Constructors **)** ##

The *TextField* class has two constructors depending on whether you want to create an empty *TextField* or one with some default text:

*TextField*类具有两个构造函数，具体取决于您要创建一个空的*TextField*还是创建一个带有默认文本的构造器：

*  To create an empty *TextField* object:
    
    要创建一个空的*TextField*对象：
    
        TextField txtFld= new TextField();
 *  To create a *TextField* with some default text use a [String literal][]:
    
    要使用一些默认文本创建*TextField* ，请使用[String文字][String literal] ：
    
        TextField txtFld = new TextField("Default Text");

**Note:** Creating a *TextField* with default text is not the same as having prompt text. The default text will remain in the *TextField* when the user clicks on it and when they do will be editable.

**注意：**使用默认文本创建*TextField*与使用提示文本不同。 当用户单击默认文本时，默认文本将保留在*TextField中* ，并且当它们可以编辑时。

## 有用的方法 **(** Useful Methods **)** ##

If you create an empty *TextField* you can set the text using the *setText* method:

如果创建一个空的*TextField* ，则可以使用*setText*方法设置文本：

txtField.setText("Another String");

To get a *String* representing the text the user entered into a *TextField* use the *getText* method:

要获取表示用户输入到*TextField中*的文本的*字符串* ，请使用*getText*方法：

String inputText = txtFld.getText();

## 事件处理 **(** Event Handling **)** ##

The default event associated with the *TextField* is the *ActionEvent*. This is triggered if the user hits *ENTER* whilst inside the *TextField* To set up the *EventHandler* for an *ActionEvent* use the *setOnAction* method:

与*TextField*关联的默认事件是*ActionEvent* 。 如果用户在*TextField*内部时按*ENTER* ，则将触发此*事件。*要为*ActionEvent*设置*EventHandler* ，请使用*setOnAction*方法：

txtFld.setOnAction(new EventHandler{
        
     @Override public void handle(ActionEvent e) {
        
     //Place the code you want to execute on the press of the ENTER key.
     }
    });

## 使用技巧 **(** Usage Tips **)** ##

Take advantage of the ability to set prompt text for the *TextField* if you need to help the user understand what the *TextField* is for. Prompt text appears in the *TextField* as slightly greyed out text. If the user clicks on the *TextField* the prompt text disappears and they have an empty *TextField* in which to input their own text. If the *TextField* is empty when it loses focus the prompt text will reappear. The prompt text will never be the [String][] value returned by the *getText* method.

如果需要帮助用户了解*TextField*的用途，请利用为*TextField*设置提示文本的功能。 提示文本在文本*字段*中显示为浅灰色的文本。 如果用户单击*TextField，*则提示文本消失，并且他们有一个空的*TextField可*在其中输入自己的文本。 如果*TextField*失去焦点时为空，则提示文本将重新出现。 提示文本永远不会是*getText*方法返回的[String][]值。

**Note:** If you create a TextField object with default text then setting the prompt text will not overwrite the default text.

**注意：**如果使用默认文本创建TextField对象，则设置提示文本将不会覆盖默认文本。

To set the prompt text for a *TextField* use the *setPromptText* method:

要设置*TextField*的提示文本，请使用*setPromptText*方法：

txtFld.setPromptText("Enter Name..");

To find out the value of the prompt text of a TextField object use the getPromptText method:

要查找TextField对象的提示文本的值，请使用getPromptText方法：

String promptext = txtFld.getPromptText();

It is possible to set a value for the number of characters a *TextField* will show. This is not the same as limiting the number of characters that can be entered into the *TextField*. This preferred column value is used when calculating the *TextField'*'s preferred width - it is only a preferred value and the *TextField* might become wider due to layout settings.

可以为*TextField*将显示的字符数设置一个值。 这与限制可以在*TextField中*输入的字符数不同。 在计算*TextField*的首选宽度时，会使用此首选列值-它只是一个首选值，由于布局设置， *TextField*可能会变宽。

To set the preferred number of text columns use the *setPrefColumnCount* method:

要设置文本列的首选数量，请使用*setPrefColumnCount*方法：

txtFld.setPrefColumnCount(25);

> 翻译自: [https://www.thoughtco.com/textfield-overview-2033936][https_www.thoughtco.com_textfield-overview-2033936]

[JavaFX]: https://www.thoughtco.com/what-is-javafx-2034192
[String literal]: https://www.thoughtco.com/the-string-literal-2034316
[String]: https://www.thoughtco.com/java-programming-4133478
[https_www.thoughtco.com_textfield-overview-2033936]: https://www.thoughtco.com/textfield-overview-2033936