Android為TV端助力 切換fragment的兩種方式

使用add方法切換時：
載入Fragment1
Fragment1 onCreate
Fragment1 onCreateView
Fragment1 onStart
Fragment1 onResume
用以下代碼切到Fragment2:

1. FragmentTransaction ft = getFragmentManager().beginTransaction();
2. ft.hide(Fragment1);
3. ft.add(R.id.simple_fragment, Fragment2);
4. ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
5. ft.commit();

Fragment1不走任何生命周期,但會調onHiddenChanged方法
Fragment2 onCreate
Fragment2 onCreateView
Fragment2 onStart
Fragment2 onResume
回到Fragment1，Remove Fragment2:

1. FragmentTransaction ft = getFragmentManager().beginTransaction();
2. ft.remove(Fragment2);
3. ft.show(Fragment1);
4. ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
5. ft.commit();

Fragment1還是不走任何生命周期，調onHiddenChanged方法
Fragment2 onPause
Fragment2 onStop
Fragment2 onDestoryView
Fragment2 onDestory
用這種方法切換，Fragment在隱藏時並不會走onDestoryView，所以顯示時也不會走onCreateView，所有View都一直保存在內存中。
用replace方法：
載入Fragment1生命周期與上面相同：
Fragment1 onCreate
Fragment1 onCreateView
Fragment1 onStart
Fragment1 onResume
切到Fragment2:

1. FragmentTransaction ft = getFragmentManager().beginTransaction();
2. ft.replace(R.id.simple_fragment, Fragment2);
3. ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
4. ft.commit();

這次的Fragment1走生命周期了
Fragment1 onPause
Fragment1 onStop
Fragment1 onDestoryView
Fragment1 onDestory
Fragment2 onCreate
Fragment2 onCreateView
Fragment2 onStart
Fragment2 onResume
真實打印出來可能是Fragment1和Fragment2混在一起的，可以看到，Fragment1走了onDestory,被完全回收了!
再切回到Fragment1

1. FragmentTransaction ft = getFragmentManager().beginTransaction();
2. ft.replace(R.id.simple_fragment, Fragment1);
3. ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
4. ft.commit();

Fragment1 onCreate
Fragment1 onCreateView
Fragment1 onStart
Fragment1 onResume
Fragment2 onPause
Fragment2 onStop
Fragment2 onDestoryView
Fragment2 onDestory
Fragment1因為已經被回收，又走onCreate，Fragment2被回收。