How i can do textField accepts only character "N or E" in Java?

Question

How i can do textField accepts only letter "N or E" in Java? doesn't accept number and another characters.

        textField.textProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue.length() > 1) textField.setText(oldValue);
            if (newValue.matches("[^\\d]")) return;
            textField.setText(newValue.replaceAll("\\d*", ""));
        });

i tryed this, this worked for maxValue. But i am need textField accept only "N" and "E" characters. So how i can do this?

Do you mean the single letter `N` or the single letter `E`? Or any combination of them, e.g. `NE`, `NNNNN`, `EEEEEE`, `ENEN`? — guninvalid, Nov 04 '21 at 12:20
Use a `TextFormatter`. Don't use a listener to modify the change. See if https://stackoverflow.com/questions/34407694/javafx-textfield-allow-only-one-letter-to-be-typed answers your question. — James_D, Nov 04 '21 at 12:22
Note also that if the user is required to choose between just two options, a `TextField` might not be the best user experience. Consider radio buttons, a check box, or a combo box instead. — James_D, Nov 04 '21 at 12:39
@James_D this is not solution for my task. this is need use only in textField — Aziz, Nov 04 '21 at 12:47

score 6 · Accepted Answer · answered Nov 04 '21 at 12:37

Use a TextFormatter. You can modify or veto the proposed change to the text. This version:

Only accepts changes where the text typed (or pasted) is "N" or "E" (either upper or lower case)
Makes the text upper case
Changes the proposed change so that it replaces existing text, instead of adding to it
Allows for deleting the current text

Your exact requirements may differ slightly. See the Javadocs for TextFormatter.Change for more details.

import java.util.function.UnaryOperator;

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

public class NorETextField extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        TextField textField = new TextField();
        UnaryOperator<TextFormatter.Change> filter = c -> {
            if (c.getText().matches("[NnEe]")) {
                c.setText(c.getText().toUpperCase());
                c.setRange(0, textField.getText().length());
                return c ;
            } else if (c.getText().isEmpty()) {
                return c ;
            }
            return null ;
        };
        textField.setTextFormatter(new TextFormatter<String>(filter));
        BorderPane root = new BorderPane(textField);
        Scene scene = new Scene(root, 400, 250);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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

}

thank you, this is worked very well. <3 – Aziz Nov 04 '21 at 12:48 — Aziz, Nov 04 '21 at 12:48

score 0 · Answer 2 · answered Nov 04 '21 at 12:33

You can try this. This accept only character N

 Pattern pattern = Pattern.compile("N");
        UnaryOperator<TextFormatter.Change> filter = c -> {
            if (pattern.matcher(c.getControlNewText()).matches()) {
                return c ;
            } else {
                return null ;
            }
        };
        TextFormatter<String> formatter = new TextFormatter<>(filter);
        textField.setTextFormatter(formatter);

How i can do textField accepts only character "N or E" in Java?

2 Answers2