JavaFX TextField throws NullPointerException

Question

This is my first time working with JavaFX, I tried to create a KeyListener (KeyTyped) that reacts to the whole scene, since I don't like to always click into textfields/areas etc.

So I got the following code:

package view;

import controller.Function;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.input.KeyEvent;
import javafx.stage.Stage;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;


public class MainGame implements Initializable {

    public TextField txtText;
    protected String word = "ABC";

    void start(ActionEvent event) throws IOException {
        URL url = new File("src/main/java/view/MainGame.fxml").toURI().toURL();
        Parent MainGame_parent = FXMLLoader.load(url);
        Scene MainGame_scene = new Scene(MainGame_parent);
        Stage primaryStage_stage = (Stage) ((Node) event.getSource()).getScene().getWindow();
        primaryStage_stage.setScene(MainGame_scene);
        primaryStage_stage.show();

        MainGame_scene.addEventFilter(KeyEvent.KEY_TYPED, (KeyEvent ev) -> {
            //System.out.println(Function.decrypt(word, txtText.getText(), ev.getCharacter().charAt(0)));
            //txtText.setText(Function.decrypt(word, txtText.getText(), ev.getCharacter().charAt(0)));
            //Function.won(word, txtText.getText());
        });
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        txtText.setText(Function.encrypt(word));
    }

}

Now, this code itself works, it just doesn't do anything if a key is pressed. The three comments would be responsible for that, but whenever I uncomment one or more, they cause a NullPointerException. I have already tried to print the different values. Every value worked except for txtText, which caused a NullPointerException.

I have tried moving it to different places, putting it into an own function, putting it into initialize, not declaring it in the class body but in the function and I also tried putting the rest of the start method in the constructor. Sadly none of those things worked.

I have no idea what to do and how to fix this. Thanks for any help!

You should add @FXML annotation before public TextField txtText; and assign id txtText to your textfield in fxml file either using scene builder or normal editing. — AbsoluteDev, Jan 05 '20 at 17:46

score 1 · Answer 1 · answered Jan 05 '20 at 15:08

1

Your TextField txtText is not initialized before you try to use it. You should do

public TextField txtText = new TextField();

instead of

public TextField txtText;

answered Jan 05 '20 at 15:08

KrazyCode123

9
2

Shouldn't fxml do that? I just tested and it seems to create a new TextField. I don't get the exception anymore, but it still doesn't change the text. – motionless Jan 05 '20 at 15:23

JavaFX TextField throws NullPointerException

1 Answers1