Delay initialization when using Fragment in Android

Question

When one fragment A is changed to another fragment B, it will call onCreate() and some other functions to do initialization. After the Fragment has

Answer 1

My Problem Is: some codes are very slow so I want to initialize a part of the datas instead of ALL of them.

I hope you're not doing heavy operations on the main UI thread.

How can I know the fragment is hide or its the current one? OR Can I get the content fragment in TabHost? OR Other ways to delay the initialization.

You could use a trick regarding the FragmentPagerAdapter. In your onPageSelected method you could find out which is the current Fragment and call an initialization method on it:

public void onPageSelected(int position) {
    //...
    Fragment item = getSupportFragmentManager().findFragmentByTag("android:switcher:" + R.id.theIdOfTheViewPager + ":" + position);
    if (item != null && item.getView() != null) {
        item.initializeStuffForThisFragment();// you need to cast it to your Fragment class 
    }
}