What event is triggered when a tab fragment is selected

问题

I'm using tab fragments in an activity and the actionbar hosts the tabs. What I want to do is that whenever a fragment appears (or re-appears) in the view (selected by the user), I start doing something. I cannot use onResume of the fragment in this case, since all tabs are never really 'paused' when the user selects another tab, so onResume is not called

I can use the two following events from the hosting activity, but I don't want them since I expect the fragment should know this logic on its own and do that task. Any idea? tks.

  @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        // When the given tab is selected, switch to the corresponding page in the ViewPager.
        mViewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    }

回答1:

Try setUserVisibleHint() in the fragment as described in this answer. When the fragment is in the selected tab, setUserVisibleHint() will be called with true, and when the fragment is not the selected tab, setUserVisibleHint() will be called with false. This works for me using the support library.

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);

    if (isVisibleToUser)
        Log.d("MyFragment", "Fragment is visible.");
    else
        Log.d("MyFragment", "Fragment is not visible.");
}

回答2:

You can override setUserVisibleHint(boolean isVisibleToUser) or onHiddenChanged (boolean hidden) method.

In case of setUserVisibleHint(boolean isVisibleToUser),
isVisibleToUser=true when fragment is visible and isVisibleToUser=false when fragment is hidden.
In case of onHiddenChanged (boolean hidden), hidden:True if the
fragment is now hidden, false if it is not visible.

回答3:

I haven't tested this, but I believe you can use the onHiddenChanged method of the Fragment

From the docs:

Called when the hidden state (as returned by isHidden() of the fragment has changed.

http://developer.android.com/reference/android/app/Fragment.html#onHiddenChanged%28boolean%29

来源：https://stackoverflow.com/questions/23970301/what-event-is-triggered-when-a-tab-fragment-is-selected

标签

android

android-tabs