Send data from Activity to Fragment already created

Question

I only have found information about how to create a Fragment sending some data to it, but only in its instantiation with the constructor.

But I want to know if it is possible to send some data (for instance, two Double objects) to a Fragment from an Activity without having to create a new instance of the Fragment.

A Fragment that has been previously created.

score 17 · Accepted Answer · answered Jul 07 '17 at 01:59

17

Just add a method in Fragment which you want to receive arguments, then invoke the method in Activity.

Activity's Code:

Fragment's Code:

answered Jul 07 '17 at 01:59

Will Tang

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17

Will, how do you declare the fragment in this case? Do you need to extend the Fragment class? – david m lee Apr 03 '19 at 17:41
sure, extends the Fragment class. @davidmlee – Will Tang Apr 08 '19 at 02:21

score 3 · Answer 2 · answered Jul 06 '17 at 23:42

You can transfer any data through a bundle like below :

Bundle bundle = new Bundle();
bundle.putInt(key, value);
your_fragment.setArguments(bundle);

Then in your Fragment, retrieve the data (e.g. in onCreate() method) with:

Bundle bundle = this.getArguments();
if (bundle != null) {
        int myInt = bundle.getInt(key, defaultValue);
}

Zach Sogolow · Answer 3 · 2017-07-06T23:45:11.940

The easiest way to do this is to define an interface in the Fragment and implement it within the activity. This link should provide a detailed example on how this can be accomplished. https://developer.android.com/training/basics/fragments/communicating.html

I think the key part you are looking for is here:

ArticleFragment articleFrag = (ArticleFragment)
      getSupportFragmentManager().findFragmentById(R.id.article_fragment);

if (articleFrag != null) {
    // If article frag is available, we're in two-pane layout...

    // Call a method in the ArticleFragment to update its content
    articleFrag.updateArticleView(position);
} else {
    // Otherwise, we're in the one-pane layout and must swap frags...

    // Create fragment and give it an argument for the selected article
    ArticleFragment newFragment = new ArticleFragment();
    Bundle args = new Bundle();
    args.putInt(ArticleFragment.ARG_POSITION, position);
    newFragment.setArguments(args);

    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

    // Replace whatever is in the fragment_container view with this fragment,
    // and add the transaction to the back stack so the user can navigate back
    transaction.replace(R.id.fragment_container, newFragment);
    transaction.addToBackStack(null);

    // Commit the transaction
    transaction.commit();
}

First try to retrieve the fragment by calling findFragmentById(R.id.fragment_id), and if it is not null you can make a call to the method you defined in your interface to send some data to it.

Send data from Activity to Fragment already created

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