getting corresponding filename of image once button pressed

Question

A Set of imagefiles are added to an arraylist(filelist2) of type File.Then an imageview and a button are affffded to a vbox,such vboxes are added to a grids of a gripane using a

Answer 1

Why not simply

System.out.println(filelist2.get(index).getName());

?

(Actually, it's not really clear to me why you create filelist2 at all. Why not do

btnar = new ArrayList<>();

for (int i=0; i < filelist1.length; i++) {
        downloadbtn = new Button("Download");
        btnar.add(downloadbtn);
        final int index=i;
        downloadbtn.setId(String.valueOf(index));
        downloadbtn.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent arg0) {
                try {
                    System.out.println("sssss");                             
                    System.out.println(filelist1[index].getName());   

                } catch (Exception ex) {
                    Logger.getLogger(HomeUI_2Controller.class.getName()).log(Level.SEVERE, null, ex);
                }


            }
        });
    }

Answer 2

Consider using a java.util.HashMap<Button, File> and calling hashMap.get(actionEvent.getSource()).getName() to get the file name.

Answer 3

I've created a DataButton which can hold some typed data (unlike userData which has the type Object). You can specify a Renderer to render the data on the button or to render an alternative text, eg. in your case: "Download".

Eg. you could use something like this:

List<Path> pathlist2 = new ArrayList<>();
...
// provide language specific text for "Download"
ResourceBundle myResourceBundle = ...;
...
DownloadRenderer downloadRenderer = new DownloadRenderer(myResourceBundle);
...
// the dafault renderer would set the text property to path.toString()
DataButton<Path> downloadbtn = new DataButton<>(downloadRenderer);
downloadbtn.setData(pathlist2.get(index));
downloadbtn.setOnAction((actionEvent) -> {
            Path path = downloadbtn.getData();
            ...   
     }); 

...

private static class DownloadRenderer extends AbstractDataRenderer<Object> {

    private final ResourceBundle myResourceBundle;

    public DownloadRenderer(final ResourceBundle myResourceBundle) {
        this.myResourceBundle = myResourceBundle;
    }

    @Override
    public String getText(Object item) {
        return myResourceBundle.getString("downloadbtn.text");
    }
} 

As you can see, you can work directly with Path objects (which should be preferred to the legacy File objects). You don't have to cast or convert the data.

Note: you could also omit the DownloadRenderer and set the text property directly:

downloadbtn.setData(pathlist2.get(index));
downloadbtn.setText(myResourceBundle.getString("downloadbtn.text"));

But then you have to make sure to call setText always after setData.

The library is Open Source and is available from Maven Central:

<dependency>
    <groupId>org.drombler.commons</groupId>
    <artifactId>drombler-commons-fx-core</artifactId>
    <version>0.4</version>
</dependency>

Answer 4

Use setUserData and getUserData to store and retrieve custom values in Nodes ! Set the fileName as the userdata and on click, retrieve it.

downloadbtn.setUserData(filelist2.get(index).getName());
downloadbtn.setOnAction(new EventHandler<ActionEvent>() {
     @Override
     public void handle(ActionEvent arg0) {
            System.out.println(downloadbtn.getUserData());   
     }