How to handle network calls inside a Fragment

Question

I have the following situation:

I have an Activity that hosts a ViewPager, and I have 4 Fragments;

the ViewPager

Answer 1

Let me introduce my idea to you:

• getCurrentItem()
  Method of ViewPager
• getItem(int position)
  Method of FragmentPagerAdapter Return the Fragment associated with a specified position.

You can define an Interface holding the method for Network I/O like

public Interface INetworkOnFragment{
 void handle(){
         //...
           }  
}

And implement it on your fragments and handle their own business logic (Network calls).

In main Activity ,set ViewPager.OnPageChangeListener on ViewPager object like here:

    pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener(){
public void onPageScrollStateChanged(int state){
//donothing
}
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels){
//donothing
}
public void onPageSelected(int position){
       INetworkOnFragment interface =(INetworkOnFragment) (pager.getAdapter().getItem(position));//get the current fragment and call handle method on it,dont need to care about whichever fragment it is . 
interface.handle()
}
});

The most important is onPageSelected(int position),Inside the callback it get the current fragment and call handle method on it,dont need to care about whichever fragment it is .

Remember the handle method are called in Activity and not in fragments.All the Network calls are implemention of Interface,which make it easy to deal in Activity.