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

public class TestKorean extends Application {

    @Override
    public void start(Stage primaryStage) {
        TextField textField = new TextField();
        textField.setTextFormatter(new TextFormatter<>(change -> change));
        Scene scene = new Scene(new StackPane(textField), 400, 200);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

}