Fragment总结

fragment是依附于Activity而存在的，fragment的生命周期总结：

首先，Activity底部有三个button分别是tab1，tab2，tab3，用来切换fragment1，fragment2，fragment3.默认是fragment1

启动Activity执行的生命周期是：

按执行顺序：

Activity：      oncreate()

fragment1： onAttach()

                     onCreate()

                     onCreateView()

                     onActivityCreated()

Activity:        onStart()

fragment1:   onStart()

Activity:        onResume()

fragment1:   onResume()

点击tab2切换fragment1到fragment2（使用replace方法切换）：

fragment1：onPause()

fragment1:  onStop()

fragment1:  onDestroyView()

fragment1:  onDestroy()

fragment1:  onDettach()

fragment2:  onAttach()

fragment2:  onCreate()

fragment2:  onCreateView()

fragment2:  onActivityCreated()

fragment2:  onStart()

fragment2:  onResume()

按返回键：

fragment2：onPause()

Activity:        onPause()

fragment2:   onStop()

Activity:        onStop()

fragment2:   onDestroyView()

fragment2:   onDestroy()

fragment2:   onDettach()

Activity:        onDestroy()

在点击tab1切换fragment1到fragment2时，再replace之后执行fragmentTransaction.addToBackStack(null);把fragment1放入回收栈中，此时生命周期：

fragment1：onPause()

fragment1:  onStop()

fragment1:  onDestroyView()

fragment2:  onAttach()

fragment2:  onCreate()

fragment2:  onCreateView()

fragment2:  onActivityCreated()

fragment2:  onStart()

fragment2:  onResume()

按返回键：

fragment2: onPause()

fragment2: onStop()

fragment2: onDestroyView()

fragment2: onDestroy()

fragment2: onDettach()

fragment1: onCreateView()

fragment1: onActivityCreated()

fragment1: onStart()

fragment1: onResume()

如果初始化的时候把fragment1，和fragment2都add上，通过hide和show来实现切换的话启动的生命周期：

Activity:      onCreate()

fragment1: onAttach()

fragment1: onCreate()

fragment1: onCreateView()

fragment1: onActivityCreate()

fragment2: onAttach()

fragment2: onCreate()

fragment2: onCreateView()

fragment2: onActivityCreated()

Activity:      onStart()

fragment1: onStart()

fragment2: onStart()

Activity:      onResume()

fragment1: onResume()

fragment2: onResume()

注：当使用hide和show进行切换是生命周期不在执行了。

按返回键：

fragment1：onPause()

fragment2:  onPause()

Activity:       onPause()

fragment1:  onStop()

fragment2:  onStop()

Activity:       onStop()

fragment1:  onDestroyView()

fragment1:  onDestroy()

fragment1:  onDettach()

fragment2: onDestroyView()

fragment2: onDestroy()

fragment2: onDettach()

Activity:      onDestroy()