CODEWITHSUNDEEP
javafxnullpointerexceptionfxmlscenestage
Michael Rodriguez-Labarca
Michael Rodriguez-Labarca

Reputation: 1

Cannot switch scenes because stage is null

I am trying to switch scenes without creating a new window. However, the stage that I initialize and set equal to the default primaryStage that JavaFX provides seems to be equal to null outside of the start method.

Here is the code:

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


@Override
public void start(Stage primaryStage) throws Exception{

    window = primaryStage;
    Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
    window.setTitle("Hello World");
    window.setScene(new Scene(root, 1000, 1000));
    window.show();
    System.out.println(window + "start");
}





public void regEvent()
{
    System.out.println(window);
   startGame(4,4);

}
private void startGame(int width, int height)
{
    System.out.println(window);
    board = new Tile[width][height];

    grid = new GridPane();
    grid.setPadding(new Insets(10,10,10,10));
    //individual cell spacing
    grid.setVgap(10);
    grid.setHgap(10);

    for(int x = 0; x< width; x++)
    {
        for(int y = 0; y< height; y++)
        {
            board[x][y] = new Tile(x,y);
            board[x][y].setText(x + " , " + y);
            GridPane.setConstraints(board[x][y], x, y);
            grid.getChildren().add(board[x][y]);
        }
    }
    Scene scene = new Scene(grid,1000,1000);
    window.setScene(scene);
    window.show();
}

When I say "window.setScene(scene)" in the startGame method, a nullpointer exception is thrown. I know that the window Stage is what is causing it, because println-ing window at the beginning of startGame returns null.

This makes no sense to me, because I initialized window at the beginning of this class, and gave it a value before startGame is even called through the start method.

Can anyone tell me how to switch the scene keeping the same stage? That's all I want to do.

Thanks guys!

Upvotes: 0

Views: 1525

Answers (1)

Oshan Mendis
Oshan Mendis

Reputation: 196

I just answered this same question that you're having here :

JavaFX Window Changer using FXML

Upvotes: 0

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