HBox inside GridPane in Javafx

Question

I have to add HBox to GridPane. If I add HBox to GridPane in same class then the system display correctly. But when I try with two classes, only empty window display.I'm new to javafx..How can I do that please help me thanks.

public class IpCamMainWindow  extends Application{

    private static ArrayList<IpCamViewer> ipCameraList = new ArrayList<IpCamViewer>();
    private static ArrayList<String> urls= new ArrayList<String>();
    GridPane grid =null;

    private ImageView imgWebCamCapturedImage;
    private BufferedImage grabbedImage;
    private ObjectProperty<Image> imageProperty = new SimpleObjectProperty<Image>();
    private Webcam webCam = null;
    private boolean stopCamera = false;
    IPview ipCamViewer=null;

    public static void main(String[] args) {


        launch(args);
    }

    @Override
    public void start(Stage stage) throws Exception {
        grid = new GridPane();
        grid.setHgap(10);
        grid.setVgap(10);
        grid.setPadding(new Insets(0, 10, 0, 10));      

        for(int i=0;i<4;i++){
            ipCamViewer = new IPview();     

            grid.add(ipCamViewer, i%2, i/2);
            System.out.println("column: " + i%2 + ", row: " + i/2);

        }

        Scene scene = new Scene(grid);
        stage.setScene(scene);
        stage.setTitle("IP Camera Solution");
        stage.show();       

    }   

}

-

public class IPview extends HBox {  

    private ImageView imgWebCamCapturedImage;
    private BufferedImage grabbedImage;
    private ObjectProperty<Image> imageProperty = new SimpleObjectProperty<Image>();
    HBox hbox;

    public IPview(){

        HBox hbox=addHBox();

    }

    public HBox addHBox() {
        hbox = new HBox();
        hbox.setPadding(new Insets(15, 12, 15, 12));
        hbox.setSpacing(10);
        hbox.setStyle("-fx-background-color: #336699;");

        Button buttonCurrent = new Button("Current");
        buttonCurrent.setPrefSize(100, 20);

        Button buttonProjected = new Button("Projected");
        buttonProjected.setPrefSize(100, 20);
        hbox.getChildren().addAll(buttonCurrent, buttonProjected);

        return hbox;
    }   

}

You need to decide if IPView is a HBox (inheritance: public class IPView extends HBox) or if IPView has a HBox (aggregation: HBox hbox). Right now you have both, and you add the buttons to the aggregated HBox, but you add the IPView itself (which contains no buttons) to the GridPane. — James_D
I need to use inheritance (public class IPView extends HBox) then want to add HBox to the Gridpane. — Milinda Saranga

James_D James_D · Accepted Answer · 2014-12-18T02:35:54

If IPView is a subclass of HBox, you need to add the buttons to the IPView instance, and not create another HBox as a member variable of it.

I.e.

public class IPview extends HBox {  

    private ImageView imgWebCamCapturedImage;
    private BufferedImage grabbedImage;
    private ObjectProperty<Image> imageProperty = new SimpleObjectProperty<Image>();

    public IPview(){

        this.setPadding(new Insets(15, 12, 15, 12));
        this.setSpacing(10);
        this.setStyle("-fx-background-color: #336699;");

        Button buttonCurrent = new Button("Current");
        buttonCurrent.setPrefSize(100, 20);

        Button buttonProjected = new Button("Projected");
        buttonProjected.setPrefSize(100, 20);
        this.getChildren().addAll(buttonCurrent, buttonProjected);

    }   

}

If you want the HBox to be a member variable, then you would not make IPView a subclass of HBox, and just provide access to the HBox:

public class IPview {  

    private ImageView imgWebCamCapturedImage;
    private BufferedImage grabbedImage;
    private ObjectProperty<Image> imageProperty = new SimpleObjectProperty<Image>();
    private HBox hbox;

    public IPview(){

        hbox = new HBox();
        hbox.setPadding(new Insets(15, 12, 15, 12));
        hbox.setSpacing(10);
        hbox.setStyle("-fx-background-color: #336699;");

        Button buttonCurrent = new Button("Current");
        buttonCurrent.setPrefSize(100, 20);

        Button buttonProjected = new Button("Projected");
        buttonProjected.setPrefSize(100, 20);
        hbox.getChildren().addAll(buttonCurrent, buttonProjected);

    }   

    public Node getView() {
        return hbox ; 
    }

}

And then in your application class you would do

        ipCamViewer = new IPview();     
        grid.add(ipCamViewer.getView(), i%2, i/2);

In general, I prefer the second approach, but that is just a matter of personal preference.

HBox inside GridPane in Javafx

1 Answers