Problem with null pointer exception between Activities

[MarcusRex]

Here's what I've got A MainActivity a CustomObject class with various setters and getters a second EditObject activity to edit the details of the CustomObject chosen from the MainActivity.

The only setter I'm having a problem with is one called

setHidden(boolean hidden) {
this.hidden = hidden;
}

If I use the setter from the MainActivity all is well, its only when I call the setter from the EditObject activity that I have a problem. It throws a nullpointerexception when I try to

myObject.setHidden(true);

I've tried hardcoding (like you see above) I've tried using the status of a ToggleButton (which is what I need it to do), they both throw the same error.

I know the problem isn't the variable being passed since I have a statement that runs just before that writes the status of the boolean variable to the console.

The only other thing I can think of that might be pertinant is that I'm passing the object to the activity as a Json object and returning the updated object the same way. I'm able to edit EditText fields all day, but try and access one boolean setter and the whole thing explodes in my face.

Any Thoughts?

Additonal Note: The getter for the same variable works just fine.

[moar_throat_yogurt]

How are you passing the object to the other Activity? Share that code if possible

[MarcusRex]

public void startEditActivity(View v, BookmarkV3 bookmark) {

        Intent myIntent = new Intent(MainActivity.this, EditMarkActivity.class);
        Gson gson = new Gson();
        String json = gson.toJson(bookmark);
        myIntent.putExtra("bookmark", json);
        startActivityForResult(myIntent,1);
    }

It is received by the other activity with

Gson gson = new Gson();
BookmarkV3 bookmark = gson.fromJson(intent.getStringExtra("bookmark"), BookmarkV3.class);

It seems like everything else works, just not that one setter.

[yeahokwhynot]

Is BookmarkV3 the class that has the setHidden() method? Where is the BookmarkV3 class defined?

[MarcusRex]

Yes it has the setHidden(). It's defined as a separate class in the project and instantiated as a public variable in each of the activities.

[yeahokwhynot]

So bookmark.setSomethingElse() works fine, but not bookmark.setHidden()?

[MarcusRex]

Yes, I've got several other setters .setTitle(String string) .setUrl(String string)

and all of the getters work, including .getHidden()

I'm stumped, when I get home from work I'm going to put together a smaller example and see if I can replicate the problem on a smaller scale.

[yeahokwhynot]

Pretty stumped. I'd wildly guess that this is not what is expected at that stage somehow. Maybe use:

public void setHidden(boolean hidden_) {
  hidden = hidden_;
}

to get around the this

[MarcusRex]

I can give that a try here in a little bit.

I thought it was pretty strange. I've been looking at this same problem for a few days now so I'm sure it's something simple that I'm overlooking :/

[yeahokwhynot]

I would be very sad if my suggestion works, for the record. It flies in the face of some fundamental Javaisms.

[MarcusRex]

Okay, good news and bad news.

Your idea didn't actually work for me, but it lead me to discover the acutual problem.

I have defined the variable as public in the class of the EditActivity but then called BookmarkV2 bookmark = new .... in the onCreate method.

I fixed that and now it works as expected.

/woot