android 怎么代码切换fragment,android 切换fragment的两种方式

使用add方法切换时：

载入Fragment1

Fragment1 onCreate

Fragment1 onCreateView

Fragment1 onStart

Fragment1 onResume

用以下代码切到Fragment2:

FragmentTransactionft =getFragmentManager().beginTransaction();

ft.hide(Fragment1);

ft.add(R.id.simple_fragment,Fragment2);

ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);

ft.commit();

Fragment1不走任何生命周期,但会调onHiddenChanged方法

Fragment2 onCreate

Fragment2 onCreateView

Fragment2 onStart

Fragment2 onResume

回到Fragment1，Remove Fragment2:

FragmentTransactionft =getFragmentManager().beginTransaction();

ft.remove(Fragment2);

ft.show(Fragment1);

ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);

ft.commit();

Fragment1还是不走任何生命周期，调onHiddenChanged方法

Fragment2 onPause

Fragment2 onStop

Fragment2 onDestoryView

Fragment2 onDestory

用这种方法切换，Fragment在隐藏时并不会走onDestoryView，所以显示时也不会走onCreateView，所有View都一直保存在内存中。

用replace方法：

载入Fragment1生命周期与上面相同：

Fragment1 onCreate

Fragment1 onCreateView

Fragment1 onStart

Fragment1 onResume

切到Fragment2:

FragmentTransactionft =getFragmentManager().beginTransaction();

ft.replace(R.id.simple_fragment,Fragment2);

ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);

ft.commit();

这次的Fragment1走生命周期了

Fragment1 onPause

Fragment1 onStop

Fragment1 onDestoryView

Fragment1 onDestory

Fragment2 onCreate

Fragment2 onCreateView

Fragment2 onStart

Fragment2 onResume

真实打印出来可能是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

FragmentTransactionft =getFragmentManager().beginTransaction();

ft.replace(R.id.simple_fragment,Fragment1);

ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);

ft.commit();

Fragment1 onCreate

Fragment1 onCreateView

Fragment1 onStart

Fragment1 onResume

Fragment2 onPause

Fragment2 onStop

Fragment2 onDestoryView

Fragment2 onDestory

Fragment1因为已经被回收，又走onCreate，Fragment2被回收。