Why do I want to avoid nondefault constructors in fragments?

Make a bundle object and insert your data (in this example your Category object). Be careful, you can't pass this object directly into the bundle, unless it's serializable. I think it's better to build your object in the fragment, and put only an id or something else into bundle. This is the code to create and attach a bundle:

Bundle args =newBundle();
args.putLong("key", value);
yourFragment.setArguments(args);

After that, in your fragment access data:

Type value = getArguments().getType("key");

That's all.

reference link:http://stackoverflow.com/questions/12062946/why-do-i-want-to-avoid-non-default-constructors-in-fragments