Android Fragment backStack 问题

Question

我的 Activity 中有以下代码:

     public void categoryClicked(int categoryId, String categoryName) {                 


ItemList newFragment = ItemList.newInstance(categoryId);
                    FragmentTransaction ft = getFragmentManager().beginTransaction();
                    ft.replace(R.id.itemContainer, newFragment);
                    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
                    ft.addToBackStack(null);           
                    ft.commit();
            }

它按预期工作，点击几次后我可以返回到之前的状态。但是，如果我只进行一次深入，则会出现以下异常:

03-10 22:17:19.895: ERROR/AndroidRuntime(23075): java.lang.IllegalStateException: Content view not yet created
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.ListFragment.ensureList(ListFragment.java:377)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.ListFragment.getListView(ListFragment.java:277)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at com.xxxxx.fragment.ItemList.onActivityCreated(ItemList.java:67)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:749)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:921)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.BackStackRecord.popFromBackStack(BackStackRecord.java:639)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.FragmentManagerImpl.popBackStackState(FragmentManager.java:1254)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:402)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.Activity.onBackPressed(Activity.java:2057)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.Activity.onKeyDown(Activity.java:1953)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.view.KeyEvent.dispatch(KeyEvent.java:2335)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.Activity.dispatchKeyEvent(Activity.java:2236)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1648)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.view.ViewRoot.deliverKeyEventPostIme(ViewRoot.java:2682)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2655)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1952)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.os.Looper.loop(Looper.java:126)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at android.app.ActivityThread.main(ActivityThread.java:3997)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at java.lang.reflect.Method.invokeNative(Native Method)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at java.lang.reflect.Method.invoke(Method.java:491)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
03-10 22:17:19.895: ERROR/AndroidRuntime(23075):     at dalvik.system.NativeStart.main(Native Method)

所以基本上，如果我只调用一次替换，当我点击后退按钮时它会出错。

此外，对于 ListFragment，我是否必须将背景设置为白色？我没有触摸它，我可以看到显示的旧 ListView ....

谢谢!

Answer 1

那么，您遇到的问题是没有可返回的 fragment 。这是你能做的。1:检查 fragment 是否存在于backstack中(通过给它一个名字)然后禁用返回2:当你第一次开始你的程序时，将一个 fragment 添加到后台堆栈，就像它被点击之前的初始状态一样。即使在这种情况下，您仍然需要进行检查以查看后台堆栈中是否还有任何内容可以返回。