JavaFX application window doesn't show when running code

Question

I'm making a javafx app and when I run it the IDE gives no errors. The application window doesn't show but I can see that the program's running in task manager.

I have tried running the code in both Eclipse and IntelliJ. I tried running a new application with just a title and it worked so it's something to do with the particular code.

package main;

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.scene.text.Font;

public class Main extends Application {
    public boolean isX=true;
    public Button[] bs=new Button[9];
    Label turn = new Label("Turn: X");
    public int i=0;

    public void start(Stage stage){
        BorderPane bp = new BorderPane();
        bp.setPrefSize(310, 350);
        turn.setFont(Font.font(20));
        bp.setTop(turn);

        makeButtons(bs);
        GridPane grid = new GridPane();
        grid.setHgap(10);
        grid.setVgap(10);

        grid.add(bs[0],0,0);
        grid.add(bs[1],1,0);
        grid.add(bs[2],2,0);
        grid.add(bs[3],0,1);
        grid.add(bs[4],1,1);
        grid.add(bs[5],2,1);
        grid.add(bs[6],0,2);
        grid.add(bs[7],1,2);
        grid.add(bs[8],2,2);

        bp.setCenter(grid);

        stage.setScene(new Scene(bp));
        stage.setTitle("Tic tac toe");
        stage.show();
    }

    void makeButtons(Button[] bs){
        while (i<bs.length){
            bs[i]=new Button(" ");
            bs[i].setFont(Font.font("Monospaced", 40));
            bs[i].setPrefSize(90, 90);
            bs[i].setOnMouseClicked(new EventHandler<MouseEvent>() {
                @Override
                public void handle(MouseEvent mouseEvent) {
                    if (isX){
                        isX=false;
                        bs[i].setText("X");
                        turn.setText("Turn: O");
                    } else {
                        isX=true;
                        bs[i].setText("O");
                        turn.setText("Turn: X");
                    }
                }
            });
        }

    }

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

Update: I finished noughts and crosses

package main;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.scene.text.Font;

public class Main extends Application {
    public boolean isX=true;
    public Button[] bs=new Button[9];
    Label turn = new Label("Turn: X");
    int goes =0;

    public void start(Stage stage){
        BorderPane bp = new BorderPane();
        bp.setPrefSize(310, 350);
        turn.setFont(Font.font(20));
        bp.setTop(turn);

        makeButtons(bs);
        GridPane grid = new GridPane();
        grid.setHgap(10);
        grid.setVgap(10);

        grid.add(bs[0],0,0);
        grid.add(bs[1],1,0);
        grid.add(bs[2],2,0);
        grid.add(bs[3],0,1);
        grid.add(bs[4],1,1);
        grid.add(bs[5],2,1);
        grid.add(bs[6],0,2);
        grid.add(bs[7],1,2);
        grid.add(bs[8],2,2);

        bp.setCenter(grid);

        stage.setScene(new Scene(bp));
        stage.setTitle("Noughts and crosses");
        stage.show();
    }

    void makeButtons(Button[] bs){
        for (int i=0;i<bs.length;i++){
            bs[i]=new Button(" ");
            bs[i].setFont(Font.font("Monospaced", 40));
            bs[i].setPrefSize(90, 90);
            bs[i].setOnAction(this::handleTurn);
        }

    }

    private void handleTurn(ActionEvent e){
        goes++;
        if (goes>4&&won()){
            return;
        }
        Button b = (Button) e.getSource();
        if (!b.getText().equals(" ")){
            return;
        }
        if (isX) {
            isX = false;
            b.setText("X");
            turn.setText("Turn: O");
        } else {
            isX=true;
            b.setText("O");
            turn.setText("Turn: X");
        }
        if (goes==9){
            turn.setText("Game over: not turns left");
        }
    }

    private boolean won(){
        //rows
        for (int i=0;i< 7;i+=3){
            if (!bs[i].getText().equals(" ")&&bs[i].getText().equals(bs[i+1].getText())&&bs[i].getText().equals(bs[i+2].getText())){
                turn.setText(bs[i].getText()+" wins!");
                return true;
            }
        }
        //columns
        for (int i=0;i<3;i++){
            if (!bs[i].getText().equals(" ")&&bs[i].getText().equals(bs[i+3].getText())&&bs[i].getText().equals(bs[i+6].getText())){
                turn.setText(bs[i].getText()+" wins!");
                return true;
            }
        }
        //diagonals
        if (!bs[0].getText().equals(" ")&&bs[0].getText().equals(bs[4].getText())&&bs[0].getText().equals(bs[8].getText())){
            turn.setText(bs[0].getText()+" wins!");
            return true;
        }

        if (!bs[2].getText().equals(" ")&&bs[2].getText().equals(bs[4].getText())&&bs[2].getText().equals(bs[6].getText())){
            turn.setText(bs[2].getText()+" wins!");
            return true;
        }
        return false;
    }

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

You can answer your own question.

Abra
– Abra

2022-01-07 10:12:52 +00:00
Commented Jan 7, 2022 at 10:12 — Abra
– Abra, Commented Jan 7, 2022 at 10:12

Abra · Accepted Answer · 2022-01-07 06:47:16Z

You aren't changing the value of i in the while loop in method makeButtons and therefore the while loop never terminates.

Also, you should add an action listener to the buttons and not a mouse listener. Refer to this tutorial.

Consider the following code.
(Note: More explanations after the code.)

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.scene.text.Font;

public class Main extends Application {
    public boolean isX=true;
    public Button[] bs=new Button[9];
    Label turn = new Label("Turn: X");

    public void start(Stage stage){
        BorderPane bp = new BorderPane();
        bp.setPrefSize(310, 350);
        turn.setFont(Font.font(20));
        bp.setTop(turn);

        makeButtons(bs);
        GridPane grid = new GridPane();
        grid.setHgap(10);
        grid.setVgap(10);

        grid.add(bs[0],0,0);
        grid.add(bs[1],1,0);
        grid.add(bs[2],2,0);
        grid.add(bs[3],0,1);
        grid.add(bs[4],1,1);
        grid.add(bs[5],2,1);
        grid.add(bs[6],0,2);
        grid.add(bs[7],1,2);
        grid.add(bs[8],2,2);

        bp.setCenter(grid);

        stage.setScene(new Scene(bp));
        stage.setTitle("Tic tac toe");
        stage.show();
    }

    void makeButtons(Button[] bs){
        int i = 0;
        while (i<bs.length){
            bs[i]=new Button(" ");
            bs[i].setFont(Font.font("Monospaced", 40));
            bs[i].setPrefSize(90, 90);
            bs[i].setOnAction(this::handleTurn);
            i++;
        }
    }

    private void handleTurn(ActionEvent event) {
        Button button = (Button) event.getSource();
        if (isX) {
            isX = false;
            button.setText("X");
            turn.setText("Turn: O");
        }
        else {
            isX = true;
            button.setText("O");
            turn.setText("Turn: X");
        }
    }

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

The above code uses method references which were introduced in Java 8. Here is the relevant line from the above code:

bs[i].setOnAction(this::handleTurn);

Whenever any of the buttons are clicked, method handleTurn is executed.

Notice that, in that method, I obtain the actual button that was clicked by calling method getSource (of class ActionEvent).

This is how it looks when I run the above code.

Collectives™ on Stack Overflow

JavaFX application window doesn't show when running code

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related