在 javaFX TextField 中设置文本颜色“不使用 CSS”

Question

If you're going to suggest CSS then don't bother, I know it works fine and is so easy to use, this is just out of curiosity and because I hate dealing with CSS while coding in Java.

JavaFX TextField undirectly extends Parent which has an "unmodifiable" ObservableList of children of type Node, and one of them has to be of type Text, so I have extended the TextField class and written two methods to check, this method to get all the children out of the TextField.

public ArrayList<Node> getAllChildren(Parent parent) {
    ArrayList<Node> res = new ArrayList<Node>();
    for (Node n : parent.getChildrenUnmodifiable()) {
        if (n instanceof Parent) {
            res.addAll(getAllChildren((Parent) n));
        } else {
            res.add(n);
        }
    }
    return res;
}

This one is to print out the result.

public void printChildren() {
    ArrayList<Node> nodes = getAllChildren(this);
    System.out.println("size = "+nodes.size()+" {");
    for (Node n : nodes) {
        System.out.println("    "+n.getClass().getSimpleName());
    }
    System.out.println('}');
}

The result is quite as expected.

size = 3 {
    Path
    Text
    Path
}

So I have written this method to get only the Text object.

private Text findText(Parent parent) {
    for (Node n : parent.getChildrenUnmodifiable()) {
        if (n instanceof Text) {
            return (Text) n;
        } else if (n instanceof Parent) {
            Text p = findText((Parent) n);
            if (p != null) {
                return p;
            }
        }
    }
    return null;
}

It worked fine and returned a Text object.

So I only needed to setFill and I would be done.

public void setTextFill(Paint p) {
    findText(this).setFill(p);
}

But whenever I try to set the textFill I get a RuntimeException that says:

Text.fill : A bound value cannot be set

That's a little long to keep up with for only setting the color for a text.

Any kind of help is appreciated.

Answer 1

The internals of Control s are hidden on purpose. In this case the text fill of the Text node is kept up to date using a binding. Unless you unbind the fill property of the node before setting it ( text.fillProperty().unbind() ), setting the value will fail.

If you want to mess around with them, you should do so using the Skin . Assuming you use JavaFX version 9 or later, the skin for TextField is part of the public API and you can access the textFill property by extending it:

@Override
public void start(Stage primaryStage) {
    TextField textField = new TextField();

    textField.setSkin(new TextFieldSkin(textField) {
        {
            // use red color for text
            setTextFill(Color.RED);
        }

    });

    StackPane root = new StackPane(textField);

    Scene scene = new Scene(root, 500, 500);

    primaryStage.setScene(scene);
    primaryStage.show();
}

If you want a subtype of TextField with a public fill property, add such a JavaFX property to your subclass and override the createDefaultSkin method to return a subclass of TextFieldSkin creating a binding for for it's textFill property.