add listener for javafx textField upto 2 decimal place

Question

I want to set javaFX text field upto two decimal places . I found the answer but it is for numeric value . e-g

 // force the field to be numeric only
textFie         


        

Answer 1

Use a text formatter on the text field. The pattern just has to match any possible decimal value with up to two decimal places. (Something like optional negative sign, followed by any number of digits, then optionally followed by a decimal point and 0-2 digits.) Just have the text formatter accept changes if the resulting text matches that pattern, and reject them otherwise.

import java.util.function.UnaryOperator;
import java.util.regex.Pattern;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.control.TextFormatter;
import javafx.scene.control.TextFormatter.Change;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class DecimalTextField extends Application {

    @Override
    public void start(Stage primaryStage) {
        Pattern decimalPattern = Pattern.compile("-?\\d*(\\.\\d{0,2})?");

        UnaryOperator<Change> filter = c -> {
            if (decimalPattern.matcher(c.getControlNewText()).matches()) {
                return c ;
            } else {
                return null ;
            }
        };

        TextFormatter<Double> formatter = new TextFormatter<>(filter);

        TextField textField = new TextField();
        textField.setTextFormatter(formatter);
        StackPane root = new StackPane(textField);
        root.setPadding(new Insets(24));

        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }

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

Answer 2

I couldn't resist. This is aboves answer in two lines (the ones that do all the work)

private static TextFormatter<Double> new3DecimalFormatter(){
        Pattern decimalPattern = Pattern.compile("-?\\d*(\\.\\d{0,3})?");
        return new TextFormatter<>(c -> (decimalPattern.matcher(c.getControlNewText()).matches()) ? c : null );
}