java - 如何使用JavaFX KeyListeners？

Question

我有一个可编辑的 JavaFX ComboBox。用户必须只能

1. 输入字母('a' 到 'z')、空格和圆括号('(', ')')以输入字符串
2. 按 Tab 退出
3. 按 Enter 键退出

如何过滤掉所有其他键、修饰符等？

我已经阅读并使用了诸如 Key_Pressed、Key_Released 之类的事件处理程序，但我无法找出实现上述目标的直接方法。 我使用的是 Mac OS Yosemite、Java 8、最新版本的 JavaFX 和
public static final EventType<KeyEvent> KEY_TYPED只是根本不起作用。下面的代码是我的尝试。变量 typedText 存储所需的值。

comboBox.addEventHandler(KeyEvent.KEY_RELEASED, new EventHandler<KeyEvent>() {
        private final String[] allowedItems = new String[]{"a","b","c","d","e","f",
        "g","h","i","j","k","l","m","n","o","p","q","r",
        "s","t","u","v","w","x","y","z"," ","(",")"};
        private final List data = Arrays.asList(allowedItems);
        private String tempInput;
        public boolean containsCaseInsensitive(String s, List<String> l){
            for (String string : l) {
                if (string.equalsIgnoreCase(s)){
                  return true;
                }
            }
            return false;
        }
        public void handle(KeyEvent event) {
            boolean b;
            b = event.isShiftDown();
            if (b) {
               if (event.getText().equals("(")) {
                    tempInput = "(";
                } else if (event.getText().equals(")")){
                    tempInput = ")";
                }
            } else {
                tempInput = event.getCode().toString().toLowerCase();
            }
            System.out.println("tempInput:"+tempInput);
            if (containsCaseInsensitive(tempInput, data)) {
            typedText = tempInput;
            System.out.println("typedText:"+typedText);
            } 
        }
    });
}

Answer 1

您可以获取编辑器(在您的情况下是一个 TextField)，并向其中添加一个 TextFormatter 以限制输入。

Tab 开箱即用，但“输入”按键是另一回事，我只是在这个示例中请求焦点。通常您会导航到焦点遍历列表中的下一项，但 JavaFX 中还没有面向 future 的 API。

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.control.TextField;
import javafx.scene.control.TextFormatter;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class ComboBoxSample extends Application {

    @Override
    public void start(Stage stage) {

        ComboBox<String> comboBox = new ComboBox<>();
        comboBox.setEditable(true);
        comboBox.getItems().addAll("A", "B", "C", "D", "E");
        comboBox.setValue("A");


        // restrict input
        TextField textField = comboBox.getEditor();
        TextFormatter<String> formatter = new TextFormatter<String>(change -> {
            change.setText(change.getText().replaceAll("[^a-z ()]", ""));
            return change;

        });
        textField.setTextFormatter(formatter);

        // dummy textfield to jump to on ENTER press
        TextField dummyTextField = new TextField();

        comboBox.addEventFilter(KeyEvent.KEY_PRESSED, e -> {
            if( e.getCode() == KeyCode.ENTER) {
                dummyTextField.requestFocus();
                e.consume();
            }
        });

        HBox root = new HBox();

        root.getChildren().addAll(comboBox, dummyTextField);

        Scene scene = new Scene(root, 450, 250);
        stage.setScene(scene);
        stage.show();

    }

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

}