creating objects and adding them to group

Question

Introduction

I want to create some Rectangles but I always see a nullPointerExeption or I cannot give as many arguments as I want. I cannot make Rectangle (width,height,x,y,paint,paint(stroke)) so I decided to use RectangleBuilder object.

Here is how I did it.

    @FXML
public void group() {
   // RB.applyTo(r);
    for (double i = 0; i < 5; i++) {

        pane.getChildren().add(new Group(g));
        r.setStroke(Color.BLACK);
        r.setY(i * 25 + 80);
        r.setX(100.0);

        r.setStroke(Color.BLACK);
        r.getParent();
        RB.y(r.getY());
        RB.x(r.getX());
        RB.height(r.getHeight());
        RB.width(r.getWidth());
        RB.stroke(r.getStroke());
        RB.fill(r.getFill());
        g.getChildren().add(RB.build());
    }

}

And here are the objects:

@FXML Pane pane = new Pane(); @FXML Rectangle r = new Rectangle(); Group g = new Group(); protected RectangleBuilder RB = null;

I do not really know if I should use RB.getX or RB.applyto(r).

Problem

is in : RB.x(r.getX()): etc.

or in RB.applyto(r); when I delete the comment marks on this line.

Problem is in RB when I try to get info about r Rectangle. I can easily turn on program but when I click on button with action "group" it gave me Error :

"NullPointerException"
"IllegalArgumentExpression"

Error Data

java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1456)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
    at javafx.event.Event.fireEvent(Event.java:171)
    at javafx.scene.Node.fireEvent(Node.java:6867)
    at javafx.scene.control.Button.fire(Button.java:179)
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:193)
    at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:336)
    at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
    at javafx.event.Event.fireEvent(Event.java:171)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3369)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3209)
    at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3164)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1582)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2267)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:250)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:173)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:292)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:530)
    at com.sun.glass.ui.View.notifyMouse(View.java:924)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:17)
    at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:67)
    at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:75)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:279)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1453)
    ... 44 more
Caused by: java.lang.NullPointerException
    at group.FXMLDocumentController.group(FXMLDocumentController.java:45)
    ... 54 more

I do not know if it is so important.

By the way line 45 is :

 RB.y(r.getY());

Whoever want to add an answer, please try to say why have you done this change because I want to learn some from that answer not only know how to solve code. — Konstanty Szymichowski, Jan 04 '15 at 12:45
possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — James_D, Jan 04 '15 at 13:11
thank for info about editing . so when i tried by this way it was giving me duplicate children error in group. and in pane when i tried to do second group — Konstanty Szymichowski, Jan 04 '15 at 21:57
last comment is about answer where he suggested not to use Rectangle Builder, just to let you know — Konstanty Szymichowski, Jan 04 '15 at 21:59
Thank for helping me. i havent ever thought that i might junst need to add Rectangle in the loop. — Konstanty Szymichowski, Jan 07 '15 at 20:35

score 0 · Accepted Answer · answered Jan 04 '15 at 14:32

Don't use RectangleBuilder, it's deprecated and will be removed.

What's your real problem? I mean, I see a lot that's wrong in your code. This is an example about how you can create rectangles in JavaFX and add them to a group:

public class RectangleDemo extends Application {

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

    @Override
    public void start(Stage primaryStage) {

        Pane pane = new Pane();

        Group group = new Group();

        for( int i = 0; i < 5; i++) {

            Rectangle rectangle = new Rectangle( 100.0, i*25.0 + 80.0, 20.0, 20.0);
            rectangle.setStroke(Color.BLACK);
            rectangle.setFill(Color.LIGHTGRAY);

            group.getChildren().add( rectangle);

        }

        pane.getChildren().add(group);

        primaryStage.setScene(new Scene( pane, 640, 480));
        primaryStage.show();
    }

}

creating objects and adding them to group

1 Answers1