Getting Null Pointer Exception while removing a layer in Javafx

Question

I have three layers Root layout, home, content (rootLayout.fxml, home.fxml and content.fxml)

        FXMLLoader loader = new FXMLLoader();
        loader.setLocation(GenerateReport.class
                .getResource("/skin/rootLayout.fxml"));
        rootLayout = (AnchorPane) loader.load();
        Scene scene = new Scene(rootLayout);


        FXMLLoader loader = new FXMLLoader();
        loader.setLocation(GenerateReport.class
                .getResource("/skin/home.fxml"));
        AnchorPane homeLayout = (AnchorPane) loader.load();
        rootLayout.getChildren().addAll(homeLayout);
        .
        .
        .
        rootLayout.getChildren().addAll(contentLayout);

like this I am adding content layout. In rootLayout.fxml i have a home button. My requiredment is if a user clicks home button then i want content layout to be removed and home layout to be visible.

content.fxml

rootLayout.fxml

In my Controller (In all the fxml file i am pointing to the same controller) class i created

@FXML
private Button home;

@FXML
private AnchorPane myContent;

@FXML
protected void homeBtn(ActionEvent event) throws Exception {
    System.out.println("click! homeBtn");
    myContent.getChildren().clear();
}

The problem i am facing is i am getting NullPointerException. i.e. myContent.getChildren() is returning null. Could anyone help me in resolving this issue.

possible duplicate of What's the difference between fx:id and id: in JavaFX? — James_D
– James_D, Commented Aug 8, 2014 at 21:17

Forager · Accepted Answer · 2014-08-08 21:57:50Z

0

You're getting a Null Pointer Exception because Javafx doesn't associate your myContent with the AnchorPane stored in the fxml, and does not attach a reference to that object.

Nodes in fxml files are given their name identifiers by using fx:id. Note, for example, that your @FXML private Button home is marked in the fxml as <Button fx:id="home"...>.

In this case, your @FXML AnchorPane myContent is marked in fxml as <AnchorPane id="myContent"...>, not <AnchorPane fx:id="myContent"...>.

id="" is used only in CSS.

answered Aug 8, 2014 at 21:57

Forager

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