How to update Android fragment from activity?

android, android-fragments

Solution

You cannot give your fragments a tag or id but you can create a custom property on your fragment class to mark them.

switch (position)
    {
    case FRAG1_POS:
        Fragment1 f = Fragment1.newInstance();
        f.fragmentType = 1;
        return f;

    case FRAG2_POS:
        Fragment1 f = Fragment1.newInstance();
        f.fragmentType = 2;
        return f;

    default:
        return null;
    }

When can then loop through all the fragments and find the one you need

List<Fragment> allFragments = getSupportFragmentManager().getFragments();
if (allFragments != null) {
    for (Fragment fragment : allFragments) {
        Fragment1 f1 = (Fragment1)fragment;
        if (f1.fragmentType == 1)
            f1.updateFragmentData();
    }
}
}

Add a public method to your fragment that will update the data in your fragment. As you have a reference to it now, you can just call it from your activity.

Problem

I want to periodically update a fragment's display based on data I download from the Internet. I have created a Timer and Runnable to periodically retrieve this data as well as a method within the fragment to update it, but I cannot seem to figure out how to gain a reference from the activity to the fragment in order to update it. I have the following code which was mostly generated by the ADT's Android Project wizard: ``` protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Log.d(tag, "onCreate()::Entering..."); setContentView(R.layout.activity_main); // Set up the action bar. final ActionBar actionBar = getSupportActionBar(); actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); // Create the adapter that will return a fragment for each of the // primary sections of the activity. mSectionsPagerAdapter = new SectionsPagerAdapter( getSupportFragmentManager()); // Set up the ViewPager with the sections adapter. mViewPager = (ViewPager) findViewById(R.id.pager); mViewPager.setAdapter(mSectionsPagerAdapter); // When swiping between different sections, select the corresponding // tab. We can also use ActionBar.Tab#select() to do this if we have // a reference to the Tab. mViewPager .setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() { @Override public void onPageSelected(int position) { actionBar.setSelectedNavigationItem(position); } }); // For each of the sections in the app, add a tab to the action bar. for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) { // Create a tab with text corresponding to the page title defined by // the adapter. Also specify this Activity object, which implements // the TabListener interface, as the callback (listener) for when // this tab is selected. actionBar.addTab(actionBar.newTab() .setText(mSectionsPagerAdapter.getPageTitle(i)) .setTabListener(this)); } ``` Here is the code used to create the tabs: ``` public class SectionsPagerAdapter extends FragmentPagerAdapter { public SectionsPagerAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int position) { // getItem is called to instantiate the fragment for the given page. switch (position) { case FRAG1_POS: return Fragment1.newInstance(); case FRAG2_POS: return Fragment2.newInstance(); default: return null; } } ``` I have tried using this solution: How to change fragment's textView's text from activity But I don't have the fragment ID. Can I create tags? If so, how do I do that in this case? Other SO posts have mentioned Bundles but I am not sending data when creating the fragment; I want to have the fragment periodically updated as data becomes available from the Activity.

Original source

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