Having trouble using getChildren()

Question

Im working on a project for school and I'm having trouble adding a child pane to a parent pane. All the code compiles except when I get to the pane.getChildren().add(Matrix); . Im able to get the code to compile when I have all the code in main, but I really want to have main call a class and create the pane there then add it to the parent pane. Im not to worried about it looking pretty right now, just want to find a way to get it to work. If anyone could help get me going in the right direction I would really appreciate it.

The compiler gives me

Button1.java:34: error: identifier expected

pane.getChildren().add(Matrix);

Button1.java:34: error: ';' expected

pane.getChildren().add(Matrix);

 public class Button1 extends Application {
public void start(Stage primaryStage) {


Scene scene = new Scene(pane, 700, 500);
primaryStage.setTitle("3 pains 1 window "); // Set the stage title
primaryStage.setScene(scene); // Place the scene in the stage
 primaryStage.show(); // Display the stage
}
 public static void main(String[] args) {
Application.launch(args);
}
GridPane pane = new GridPane();
MatrixPane Matrix = new MatrixPane();
pane.getChildren().add(Matrix);

}

class MatrixPane extends Pane {

double HEIGHT = 500;
double WIDTH = 200;
private GridPane pane = new GridPane();


public MatrixPane() {
}

public void fillpane() {

for (int i = 0; i < 10; i++) {
        for (int j = 0; j < 10; j++) {
            TextField text = new TextField(Integer.toString((int)(Math.random() * 2)));
            text.setMinWidth(WIDTH / 8.0);
            text.setMaxWidth(WIDTH / 10.0);
            text.setMinHeight(HEIGHT / 8.0);
            text.setMaxHeight(HEIGHT / 10.0);
                pane.add(text, j, i);
        }
    }

}


}

Answer 1

That line have to be inside of a method, I suggest that it should be inside of start

public void start(Stage primaryStage) {
   pane.getChildren().add(Matrix);
   ...