Question

我遇到了JavaFX textformatter的问题。我想知道我做错了什么或者Java JDK中有错误。

以下是显示问题的代码：

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.control.TextFormatter;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

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

    @Override
    public void start(Stage primaryStage) {
        TextField field = new TextField("test0");
        field.setTextFormatter(new TestTextFormatter());
        Button btn = new Button();
        btn.setText("Test");
        btn.setOnAction(e -> {
            field.setText(null);
            field.setText("test");
        });
        BorderPane root = new BorderPane();
        root.setTop(btn);
        root.setCenter(field);
        primaryStage.setScene(new Scene(root, 300, 250));
        primaryStage.show();
    }
    class TestTextFormatter extends TextFormatter<String> {
        public TestTextFormatter() {
            super(c -> {
                System.out.println("newControlText=" + c.getControlNewText());
                return c;
            });
        }
    }
}

点击按钮几次。第一次按预期工作输出是： newControlText = TEST0 newControlText = newControlText =测试

第二次和每次下一次尝试都会导致异常：

Exception in thread "JavaFX Application Thread" java.lang.IllegalArgumentException: The start must be <= the end
    at javafx.scene.control.TextInputControl.getText(TextInputControl.java:446)
    at javafx.scene.control.TextInputControl$TextInputControlFromatterAccessor.getText(TextInputControl.java:1609)
    at javafx.scene.control.TextFormatter$Change.getControlNewText(TextFormatter.java:453)
    at TestApp$TestTextFormatter.lambda$0(TestApp.java:34)
    at javafx.scene.control.TextInputControl.filterAndSet(TextInputControl.java:1165)
    at javafx.scene.control.TextInputControl.access$900(TextInputControl.java:79)
    at javafx.scene.control.TextInputControl$TextProperty.doSet(TextInputControl.java:1410)
    at javafx.scene.control.TextInputControl$TextProperty.set(TextInputControl.java:1323)
    at javafx.scene.control.TextInputControl.setText(TextInputControl.java:349)
    at TestApp.lambda$0(TestApp.java:21)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
...

你能帮我理解哪里有问题（我的代码还是JDK）？

Answer 1

请查看此答案https://stackoverflow.com/a/32893573/814304

您正在尝试更改事件内的文本，这正是您不想做的事情。

Answer 2

这是一个过滤器，在应用方法c.getControlNewText()时会引发异常。

如果您的代码允许设置空值，则应按以下方式重写TestTextFormatter类

class TestTextFormatter extends TextFormatter<String> {
    public TestTextFormatter() {
        super(c -> {
            if ( ((TextField)c.getControl()).getText() == null ) {
                return c;
            }
            System.out.println("newControlText=" + c.getControlNewText());
            return c;
        });
    }
}

带有空文本的JavaFX TextFormatter问题

2 个答案: