方向更改:DialogFragment可见时IllegalStateException

Question

我想让Android处理方向更改.不幸的是,每次打开对话框并发生方向更改时它都会崩溃.我已经怀疑原因但不知道如何处理它:

应用程序首次启动backstack时看起来像这样:

02-07 15:25:36.517: I/System.out(14541): Added Fragments:
02-07 15:25:36.517: I/System.out(14541):   #0: PortraitModeFragment{41963330 #0 id=0x7f090001 ListViewFragment}

好的,现在我们打开一个对话框:

02-07 15:26:03.316: I/System.out(14541): Added Fragments:
02-07 15:26:03.316: I/System.out(14541):   #0: PortraitModeFragment{41963330 #0 id=0x7f090001 ListViewFragment}
02-07 15:26:03.326: I/System.out(14541):   #1: MyDialogFragment{4199f6a0 #1 MyDialogFragment}

现在旋转设备时:

02-07 15:26:37.502: E/AndroidRuntime(14541): FATAL EXCEPTION: main
02-07 15:26:37.502: E/AndroidRuntime(14541): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.testapp/com.example.testapp.MainActivity}: android.view.InflateException: Binary XML file line #11: Error inflating class fragment
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3692)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.ActivityThread.access$700(ActivityThread.java:141)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1240)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.os.Looper.loop(Looper.java:137)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.ActivityThread.main(ActivityThread.java:5039)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at java.lang.reflect.Method.invokeNative(Native Method)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at java.lang.reflect.Method.invoke(Method.java:511)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at dalvik.system.NativeStart.main(Native Method)
02-07 15:26:37.502: E/AndroidRuntime(14541): Caused by: android.view.InflateException: Binary XML file line #11: Error inflating class fragment
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:270)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.Activity.setContentView(Activity.java:1881)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at com.example.testapp.MainActivity.onCreate(MainActivity.java:17)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.Activity.performCreate(Activity.java:5104)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
02-07 15:26:37.502: E/AndroidRuntime(14541):    ... 12 more
02-07 15:26:37.502: E/AndroidRuntime(14541): Caused by: java.lang.IllegalStateException: Fragment com.example.testapp.fragments.LandscapeModeFragment did not create a view.
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:303)
02-07 15:26:37.502: E/AndroidRuntime(14541):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:676)

有趣的事实:如果我首先转动设备并随后打开对话框并更改方向,则不会发生这种情况,因为这两个片段都是预先加载并在后台堆栈中安静地存在:

02-07 15:34:00.015: I/System.out(15412):   #0: PortraitModeragment{419b99b0 #0 id=0x7f090001 ListViewFragment}
02-07 15:34:00.015: I/System.out(15412):   #1: LandscapeModeFragment{419b9b88 #1 id=0x7f090003 LandscapeModeFragment}
02-07 15:34:00.025: I/System.out(15412):   #2: MyDialogFragment{419d1da0 #2 MyDialogFragment}

在使用我的应用程序之前,我无法让用户旋转智能手机,那么该怎么办？;)

重现:

我如何将Dialog添加到backstack:

MyDialogFragment myTvShowDialog = new MyDialogFragment();
myTvShowDialog.show(getActivity().getSupportFragmentManager(),myTvShowDialog.TAG);

我做的是为MainActivity创建两个xml文件:

1.res/layout/main.xml(PortraitMode):

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">
     <TextView android:id="@+id/textView1" android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text="layout-land/PORTRAIT" />
     <fragment class="com.example.testapp.fragments.PortraitModeFragment"
                        android:id="@+id/fragment" android:layout_weight="1"
                        android:layout_width="0px" android:layout_height="match_parent" android:tag="PortraitModeFragment">
     </fragment>
</LinearLayout>

---

2.res/layout-land/main.xml(LandscapeMode)

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" android:orientation="vertical">
    <TextView   android:id="@+id/textView1"   android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="layout-land/LANDSCAPE" />
    <fragment class="com.example.testapp.fragments.LandscapeModeFragment"
            android:id="@+id/LandscapeModeFragment" android:layout_weight="1"
            android:layout_width="0px" android:layout_height="0dp" android:tag="LandscapeModeFragment">
     </fragment>
</LinearLayout>

MainActivity.java:

public class MainActivity extends FragmentActivity {
    private static final String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.v(TAG, "onCreate()");
        setContentView(R.layout.activity_main);
        getSupportFragmentManager().dump("", null,
                new PrintWriter(System.out, true), null);
    }
}

FragmentPortraitMode:

public class PortraitModeFragment extends Fragment {
    @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View fragment = inflater.inflate(R.layout.portraitmodefragment_layout,
            null);
    Button findViewById = (Button) fragment.findViewById(R.id.button1);
    findViewById.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            MyDialogFragment myDialog = new MyDialogFragment();
            myDialog.show(getActivity().getSupportFragmentManager(),
                    MyDialogFragment.TAG);
        }
    });
    TextView textView = (TextView) fragment.findViewById(R.id.textView1);
    textView.setText(TAG);
    return fragment;
}

片段LandscapeMode:

public class LandscapeModeFragment extends Fragment {

    public static final String TAG = "LandscapeModeFragment";

    @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View fragment = inflater.inflate(R.layout.landscapemode_fragment_layout,
            container, false);
    return fragment;
}
}

landscapemode_fragment_layout.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
            <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="LANDSCAPEFRAGMENT" />
</LinearLayout>

portraitmode_fragment_layout_xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <Button   android:id="@+id/button1"    android:layout_width="wrap_content"    android:layout_height="wrap_content"     android:text="Button" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView" />

</LinearLayout>

Answer 1

好吧,我发现了一个同样好的解决方法.

第一:问题是什么？

layout-xml中定义的片段和每个FragmentManager添加的片段具有不同的生命周期abd,尽管可能会使用FragmentManager意外行为(异常)来处理布局片段导致应用程序崩溃.

正如Dianne Hackborn在Google Groups Forum中提到的那样

在XML中定义片段主要用于将要保留的内容.如果要添加和删除,您应该始终如一地动态地执行此操作.

我可以在将来的版本中查看这个内容,但是请注意,无论我做什么,您都可以轻松地使用它来处理不良情况 - 例如,如果您没有针对片段的唯一包含视图组,那么会发生什么在层次结构中的该点删除/添加片段将表现不一致.

所以我们不允许混合世界(FragmentManager-Fragments和LayoutXML-Fragments).不幸的是,这也涉及在运行时添加的DialogFragments.会发生什么:Android-Framework添加了方向 - 将新布局创建的Fragment更改为backstack.FragmentManager尝试在与新创建的Layout-Fragment相同的索引上添加DialogFragment.这就是当事情变得混乱并发生IllegalStateException时.

那么,解决方法是什么？

大多数使用Fragments用于不同方向的示例涉及将FrameLayout定义为容器,以将正确的Fragment放入其中.所以我们将使用FragmentManager一路走来,并从我们的设计中取消LayoutFragments:

ActivityMain只使用这个简单的xml作为其contentView:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/fragment_container_id"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent">
</FrameLayout>

并在启动时将正确的片段注入容器中

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mainactivity_framelayout);
    createFragmentIfNotExits();
}
private void createFragmentIfNotExits() {
    int orientation = getResources().getConfiguration().orientation;
    Fragment newFragment;
    if (orientation == Configuration.ORIENTATION_PORTRAIT) {
        newFragment = new TvShowListPortraitModeFragment();
    } else {
        newFragment = new TvShowListLandscapeModeFragment();
    }
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    ft.replace(R.id.fragment_container_id, newFragment);
    ft.commit();
}

缺点: 不幸的是,保留已保存的碎片状态是不可能的.或者至少我还需要弄清楚如何做到这一点.

这么多来自我.我不会将这个答案标记为"已回答",因为我没有真正使其成功,也许有人会弄明白并发布一个更简单的解决方案.我会在当时标记为正确.