javafx: how to addEventHandler for javafx textfield for validating time

Question

I have hard time finding any guides on how to addEventHandlerfor textfield so that it does real time validation from key inputs to only allow hh:mm time format. I found this expression ^([0-9]|0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]$ but don't know how to add it to the eventHandler. Also I was trying to use simpleDateFormat but with no success.

Edit: I'm trying to to make something like this (this was with JFrame):

JTextField iegadesVerTesksts = new JTextField();
panel.add(iegadesVerTesksts);
iegadesVerTesksts.addKeyListener(new KeyAdapter() {
        public void keyTyped(KeyEvent evt) {
            char c = evt.getKeyChar();
            if ((!(Character.isDigit(c) || (c == KeyEvent.VK_BACK_SPACE) || c == KeyEvent.VK_DELETE))
                    &&evt.getKeyChar()!='.') {
                evt.consume();
            }
            if(evt.getKeyChar()=='.'&&iegadesVerTesksts.getText().contains(".")){
                evt.consume();
            }
        }
    });

Right now with JavaFX I have created main and piezimes.java. In product class I define objects I want to create:

public class Piezimes {
private LocalDate datums;
private String laiks;
private String piezime;

public Piezimes(){
    this.datums = null;
    this.laiks = "";
    this.piezime = "";
}

public Piezimes (LocalDate datums, String laiks, String piezime ){
    this.datums = datums;
    this.laiks = laiks;
    this.piezime = piezime;
}

public LocalDate getDatums() {

    return datums;
}

public void setDatums(LocalDate datums) {

    this.datums = datums;
}

public String getLaiks() {

    return laiks;
}

public void setLaiks(String laiks) {
    this.laiks = laiks;
}

public String getPiezime() {

    return piezime;
}

public void setPiezime(String piezime) {

    this.piezime = piezime;
}

}

And In main.java I have created tableView where at the end I added buttons where I call .getText so I can user input. Only with time validation I have problems with. Method right now that I call to add user input to table is: piezimes.setLaiks(laiksIevade.getText());

Answer 1

To be honest I am not very familiar with TextFormatter. Every time I want to do something like this I am doing a custom TextField in which I add a changeListener to the textProperty and check the user's input matches a regex. Now in your situation you will need to add at least one more to the focusedProperty in order to check if the user left the input incomplete and I would recommend to add one more to catch action events. Now I am not a master with regular expressions so be lenient xD. Here is my implementation :

class CustomField extends TextField {

        public CustomField() {
            super();
            textProperty().addListener(new ChangeListener<String>() {
                @Override
                public void changed(ObservableValue<? extends String> observable, String oldValue, String newValue) {
                    if (newValue.isEmpty())
                        return;

                    if (newValue.matches("\\d{1,2}|\\d{1,2}:|\\d{1,2}:[0-5]?[0-9]")) {
                        setText(newValue);
                    } else {
                        setText(oldValue);
                    }
                }
            });

            setOnAction(e -> {
                if (!getText().matches("\\d{2}:\\d{2}")) {
                    setText("");
                }
            });

            focusedProperty().addListener(new ChangeListener<Boolean>() {
                @Override
                public void changed(ObservableValue<? extends Boolean> arg0, Boolean oldPropertyValue,
                        Boolean newPropertyValue) {
                    if (!newPropertyValue) {
                        if (!getText().matches("\\d{2}:\\d{2}")) {
                            setText("");
                        }
                    }
                }
            });
        }
    }

While the user write something to the textField all you need to do is to check if it matches the NN:XN (N = number 0-9 & X = number 0-5 ) or just a portion of it. When the input is finished you will check if it matches to your format and only then you will let it be, otherwise set the textfield content to "".

Of course I am not saying this is the right way or at the best one, but it's a 'workaround' for people like me who don't know about the TextFormatter :P