如何动态更改 JavaFX TextArea 中文本的前景色？

Question

I am using JavaFX 8 and have a read-only TextArea that displays either a confirmation message or an error message, depending on the situation. I want confirmation messages to have black text but I want error messages to have red text. How do I do that in JavaFX 8? For the moment, I'd prefer to do it programmatically but I would certainly be interested in how that could be done in FXML as well for the next draft of the program.

Essentially, I am displaying a tableView and letting the user edit the information in the cells of the TableView. If the user puts an invalid value in the cell, I want to give him/her a clear error message about what's wrong and I'd like that message to be red (or highlighted in some way). If they change the value in an acceptable way, I want a confirmation message that tells them they've changed the value successfully in the table and the database; I'd prefer that message is black (or similar).

I'm fairly new to JavaFX and am surprised to find that there is no setForeground() any more. How are we supposed to do this now? Or should I be using some kind of HTML field? I haven't played with those yet....

======================================================================= Followup question

I may be misunderstanding the intent of James_D's answer but I created TWO pseudoclasses, one for error messages and one for informational messages:

private static final PseudoClass ERROR =                               PseudoClass.getPseudoClass("error");

private static final PseudoClass INFO = PseudoClass.getPseudoClass("info");   

I had hoped to be able to have a simple method that could write EITHER kind of message, informational or error, simply by passing the pseudoclass to the method. Here's the method:

private void writeMessage(String message, PseudoClass pseudoClass) {

    messageArea.pseudoClassStateChanged(pseudoClass, true);
    messageArea.setText(message);
}

I invoke the method as follows for an error message:

writeMessage("This is an error message.", ERROR);

and this way for an information message:

writeMessage("This is an information message.", INFO);

And this is what I added to my CSS file:

.text-area:error {
-fx-text-fill: red ;
-fx-font-weight: 700;
}   

.text-area:info {
-fx-text-fill: black;
-fx-font-weight: normal;
 }

Why don't my error messages show up as bold? (All messages appear in normal font.) Why do some error messages not show up as red? I consistently invoke writeMessage() the same way throughout.

Answer 1

In JavaFX, you style controls using CSS. The recommended way is to use an external style sheet, which separates the style (in the CSS file) from the logic (in Java). You can also use an "inline" style by directly calling setStyle(...) on a control.

According to the CSS documentation , TextArea s have a CSS property -fx-text-fill which defines the color of the text that is displayed.

So the "quick and dirty" way could be:

private TextArea messageArea ;

// ...

private void showMessage(String message, boolean error) {
    if (error) {
        messageArea.setStyle("-fx-text-fill: red ;") ;
    } else {
        messageArea.setStyle("");
    }
    messageArea.setText(message);
}

A better approach is to define your own CSS PseudoClass , and then to reference it in an external style sheet:

private static final PseudoClass ERROR = PseudoClass.getPsuedoClass("error");

private TextArea messageArea ;

// ...

private void showMessage(String message, boolean error) {
    messageArea.pseudoClassStateChanged(ERROR, error);
    messageArea.setText(message);
}

Your CSS file can now define how error messages are styled:

.text-area:error {
    -fx-text-fill: red ;
}

and then you can attach the stylesheet to the scene with

Scene scene = ... ;
scene.getStylesheets().add("path/to/css/file");

Answer 2

textArea.setTextFill(Color.WHITE); works for me.