title: replaced Fragment can't load data
body: <p>the first time to replace and load fragment data is fine.but replace the fragment again, the new fragment can't load data.</p>
  
  <p>for example if the fragment have a button, click it will show an invisible textView. the first fragment can show the textView,but replace to the second fragment(same code) can't show it.</p>
  
  <pre><code>private void startHomeFragment() {
      mDiscoveryFragment = new AskQuestionFragment();
      beginTransaction(FirsthomeFragment);
  }
  
  private void beginTransaction(Fragment fragment) {
      FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
      ft.replace(R.id.fragment_container, fragment);
      ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
      ft.commit();
  }
  
  
  public void onItemChanged(int index) {
      switch (index) {
          case replace to the second:
              SecondFragment secondFragment= new secondFragment;
              beginTransaction(secondFragment);
              break;
  </code></pre>