Java.lang.runtimeexception: Unable To Start Activity Componentinfo, Unable To Instantiate Fragment, Could Not Find Fragment Constructor

Please see all the four pictures, first 3 pictures has error screen, the last one has Fragment constructor. https://i.stack.imgur.com/lbodG.png https://i.stack.imgur.com/nysfG.

Solution 1:

You must have a default constructor for Fragment.

publicclassTab1FragmentextendsFragment{

publicTab1Fragment(){
}
...
}

If you want to pass data to your fragment you must do that by setArguments(), not by passing it through constructor, not good practice. Instead try something like this:

publicclassTab1FragmentextendsFragment{
    privatestaticfinalStringARG_URL="url";
    publicTab1Fragment(){
    }
    publicstatic Tab1Fragment newInstance(String url) {
            Tab1Fragmentfragment=newTab1Fragment();
            Bundleargs=newBundle();
            args.putString(ARG_URL, url);
            fragment.setArguments(args);
            return fragment;
        }
}

And to get url value in fragment use

getArguments().getString(ARG_URL);

Now use newInstance method to get fragment instance.

Tab1Fragment.newInstance("your url");

Solution 2:

As @Mangal mentioned, a Fragment must have a default (no argument) constructor. To pass data to a new fragment, use a static function, like this

publicstatic MyFragment newInstance(String someData) {
    MyFragmentfragment=newMyFragment ();
    Bundleargs=newBundle();
    args.putString("someData", someData);
    fragment.setArguments(args);
    return fragment;
}

and retrieve the data like this

@OverridepublicvoidonActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    Bundleargs= getArguments();
    StringsomeData="";
    if( args != null ) {
        someData = args.getString("someData", "");
    }
}

Then, instead of calling

new MyFragment(data);

in the code where you create the Fragment, you would instead call

MyFragment.getInstance(data);