java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState

今天在开发的时候遇到了一个IllegalStateException, 如下所示：

java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState    at android.support.v4.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1842)    at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1860)    at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:650)    at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:609)    at cn.collabtech.teacher.home.HomeActivity.replaceFragment(HomeActivity.java:158)    at cn.collabtech.teacher.home.HomeActivity.switchToClassRoomView(HomeActivity.java:445)    at cn.collabtech.teacher.home.HomeActivity$HomeReceiver.onReceive(HomeActivity.java:516)    at android.support.v4.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:297)    at android.support.v4.content.LocalBroadcastManager.access$000(LocalBroadcastManager.java:46)    at android.support.v4.content.LocalBroadcastManager$1.handleMessage(LocalBroadcastManager.java:116)    at android.os.Handler.dispatchMessage(Handler.java:102)    at android.os.Looper.loop(Looper.java:136)    at android.app.ActivityThread.main(ActivityThread.java:5017)    at java.lang.reflect.Method.invokeNative(Native Method)    at java.lang.reflect.Method.invoke(Method.java:515)    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:933)    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749)

看到onSaveInstanceState后一想，这个错误确实是发生在把activity隐藏后，activity收到通知在“后台”做replace fragment的操作所导致的。网上查了一下，有两种解决方案：

方案1： 在activity里面加入一个状态表示，比如DISPLAY_FRAGMENT， 然后在恢复显示activity的时候根据状态去显示相应的fragment,

@Overrideprotected void onResume(){    super.onResume();    if (state == DISPLAY_FRAGMENT) {        // do something: display fragment    } else {        // balabala...    }

方案2： 用FragmentTransaction.commitAllowingStateLoss() 代替FragmentTransaction.commit()