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ITreeContentProvider with java.nio.file.Path; [message #1851047]

Fri, 25 March 2022 15:50

Andrei Buzdugan

Messages: 4
Registered: March 2022

Junior Member

Hello

I'm new to the Eclipse platform and RCP, and started with the Lars Vogel and Packt books on the topic. There they treat the TreeViewer content provider with the FIle class (java,io.file). I want to tray with the new java.nio.file package. However, after executing the getElements routine, the next one, hasChildren isn't called if output from the previous one is Path[] class type, but for File[] works okay.

public class FileProvider implements ITreeContentProvider, IResourceChangeListener{

@Override
public Object[] getElements(Object inputElement) {
Path[] paths;
if (inputElement instanceof Object) {
try {
paths = Files.list((Path) inputElement).toArray(Path[]::new);
} catch (IOException e) {
// TODO Auto-generated catch block
paths = new Path[0];
e.printStackTrace();
}
} else {
//Do nothing, as long as only input is from Path class
paths = new Path[0];
}
return paths;
}

Anyone know why ?

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Re: ITreeContentProvider with java.nio.file.Path; [message #1851048 is a reply to message #1851047]

Fri, 25 March 2022 16:07

Nitin Dahyabhai

Messages: 4341
Registered: July 2009

Senior Member

What are you returning from this method when you find that hasChildren isn't being called--what's in the array?

Nitin Dahyabhai
Eclipse Web Tools Platform

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Re: ITreeContentProvider with java.nio.file.Path; [message #1851049 is a reply to message #1851048]

Fri, 25 March 2022 16:27

Rolf Theunissen

Messages: 259
Registered: April 2012

Senior Member

Probably your code throws a ClassCastException, which is not caught properly.

Hint:

inputElement instanceof Object

is always true.

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Re: ITreeContentProvider with java.nio.file.Path; [message #1851050 is a reply to message #1851049]

Fri, 25 March 2022 16:48

Andrei Buzdugan

Messages: 4
Registered: March 2022

Junior Member

No exception. I've added a simple print in the catch block and it doesn't show.

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Re: ITreeContentProvider with java.nio.file.Path; [message #1851051 is a reply to message #1851048]

Fri, 25 March 2022 16:52

Andrei Buzdugan

Messages: 4
Registered: March 2022

Junior Member

Hard to say as there are many fields. But mostly is populated with paths of files in the selected workspace. For instance I've added a simple print, right before return, to check that I have the expected data there to work with and it;s okay, the array is populated with what files I have (ex : b.txt)

for (int i = 0; i < paths.length; i++) {
System.out.println(paths[i].getFileName());
}

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Re: ITreeContentProvider with java.nio.file.Path; [message #1851056 is a reply to message #1851051]

Fri, 25 March 2022 18:29

Ed Merks

Messages: 32818
Registered: July 2009

Senior Member

The debugger is your best friend. It can answer every question faster than posting a question to a forum.

Ed Merks
Professional Support: https://www.macromodeling.com/

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Re: ITreeContentProvider with java.nio.file.Path; [message #1851203 is a reply to message #1851056]

Wed, 30 March 2022 13:30

Andrei Buzdugan

Messages: 4
Registered: March 2022

Junior Member

Followed advice, was hoping for a quick solution. Problem came from my side. In my original understanding, I thought that after getElements() function, the next one to be called is the hasChildren(). Not true for me, because I had a comparator functionality implemented. And that one wasn't handling the Path class, but the File class.

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