java 仅在微调控件中插入数字

Insert only numbers in Spinner Control

提问by user1285928

I tested Spinner control in Java 8u40

我在 Java 8u40 中测试了 Spinner 控件

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.Spinner;
import javafx.scene.control.SpinnerValueFactory;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class MainApp extends Application
{
    public static void main(String[] args)
    {
        Application.launch(args);
    }

    @Override
    public void start(Stage stage)
    {
        final Spinner spinner = new Spinner();

        spinner.setValueFactory(new SpinnerValueFactory.IntegerSpinnerValueFactory(0, 10000));
        spinner.setEditable(true);

        GridPane grid = new GridPane();
        grid.setHgap(10);
        grid.setVgap(10);
        grid.setPadding(new Insets(10));

        int row = 0;

        grid.add(new Label("Spinner:"), 0, row);
        grid.add(spinner, 1, row);

        Scene scene = new Scene(grid, 350, 300);

        stage.setTitle("Hello Spinner");
        stage.setScene(scene);
        stage.show();
    }
}

How I can only insert number into the spinner control field?

我如何只能在微调控件字段中插入数字？

Now I can insert numbers and text. Is there any example that can be used as example?

现在我可以插入数字和文本了。有什么例子可以作为例子吗？

回答by kleopatra

Not entirely certain about the requirement - assuming that you want to prevent the input of characters that wouldn't parse to a valid Number.

不完全确定要求 - 假设您想防止输入无法解析为有效数字的字符。

If so, usage of a TextFormatter in the Spinner's editor comes to the rescue: with it, you'll monitor any change of text and either accept or reject it. The decision is encapsulated inside the formatter's filter. A very simple version (there's definitely more to do, see Swing's DefaultFormatter)

如果是这样，在 Spinner 的编辑器中使用 TextFormatter 就派上用场了：有了它，您将监视文本的任何更改并接受或拒绝它。该决定封装在格式化程序的过滤器中。一个非常简单的版本（肯定还有更多的事情要做，请参阅 Swing 的 DefaultFormatter）

// get a localized format for parsing
NumberFormat format = NumberFormat.getIntegerInstance();
UnaryOperator<TextFormatter.Change> filter = c -> {
    if (c.isContentChange()) {
        ParsePosition parsePosition = new ParsePosition(0);
        // NumberFormat evaluates the beginning of the text
        format.parse(c.getControlNewText(), parsePosition);
        if (parsePosition.getIndex() == 0 ||
                parsePosition.getIndex() < c.getControlNewText().length()) {
            // reject parsing the complete text failed
            return null;
        }
    }
    return c;
};
TextFormatter<Integer> priceFormatter = new TextFormatter<Integer>(
        new IntegerStringConverter(), 0, filter);

spinner.setValueFactory(new SpinnerValueFactory.IntegerSpinnerValueFactory(
        0, 10000, Integer.parseInt(INITAL_VALUE)));
spinner.setEditable(true);
spinner.getEditor().setTextFormatter(priceFormatter);

回答by Marcus Bleil

• because Spinner uses TextField as an editor, users can insert any String into spinner
• only after user hits the return key then Spinners model (SpinnerValueFactory implementation) validates users input

• 因为 Spinner 使用 TextField 作为编辑器，所以用户可以在 Spinner 中插入任何 String
• 只有在用户点击返回键后，Spinners 模型（SpinnerValueFactory 实现）才会验证用户输入

so you have to add validation to Spinners editor by code:

所以你必须通过代码向 Spinners 编辑器添加验证：

// imports omitted

public class MainApp extends Application {

protected static final String INITAL_VALUE = "0";

public static void main(String[] args) {
    Application.launch(args);
}

@Override
public void start(Stage stage) {
    final Spinner spinner = new Spinner();

    spinner.setValueFactory(new SpinnerValueFactory.IntegerSpinnerValueFactory(0, 10000,
            Integer.parseInt(INITAL_VALUE)));
    spinner.setEditable(true);

    EventHandler<KeyEvent> enterKeyEventHandler;

    enterKeyEventHandler = new EventHandler<KeyEvent>() {

        @Override
        public void handle(KeyEvent event) {

            // handle users "enter key event"
            if (event.getCode() == KeyCode.ENTER) {

                try {
    // yes, using exception for control is a bad solution ;-)
            Integer.parseInt(spinner.getEditor().textProperty().get());
                }
                catch (NumberFormatException e) {

                    // show message to user: "only numbers allowed"

                    // reset editor to INITAL_VALUE
                    spinner.getEditor().textProperty().set(INITAL_VALUE);
                }
            }
        }
    };

    // note: use KeyEvent.KEY_PRESSED, because KeyEvent.KEY_TYPED is to late, spinners
    // SpinnerValueFactory reached new value before key released an SpinnerValueFactory will
    // throw an exception
    spinner.getEditor().addEventHandler(KeyEvent.KEY_PRESSED, enterKeyEventHandler);

    GridPane grid = new GridPane();
    grid.setHgap(10);
    grid.setVgap(10);
    grid.setPadding(new Insets(10));

    int row = 0;

    grid.add(new Label("Spinner:"), 0, row);
    grid.add(spinner, 1, row);

    Scene scene = new Scene(grid, 350, 300);

    stage.setTitle("Hello Spinner");
    stage.setScene(scene);
    stage.show();
}
}

• try with not numbers: code will replace spinners editor content with INITIAL_VALUE
• try with numbers out of border, spinners model will reset spinners editor to valid value

• 尝试不使用数字：代码将用 INITIAL_VALUE 替换微调器编辑器内容
• 尝试使用超出边界的数字，微调模型会将微调编辑器重置为有效值