android.view.InflateException: 二进制XML文件第28行：加载fragment类时出错

Question

我正在开发一个具有导航抽屉和碎片显示数据的应用程序。这是我的应用程序活动堆栈：

- > 登录（检查是否已登录，跳过加载视图并继续到时间轴） - > 时间轴 我遇到错误的方式如下：

- > 启动应用程序 - > 它会跳过登录屏幕，因为我已经登录了 - > 一切看起来都很好，然后我从菜单抽屉中点击注销或按下返回按钮 - > 我回到登录屏幕 - > 现在如果我再次按下登录并重新启动时间轴活动，我的应用程序将崩溃... 以下是代码。这是日志记录：

11-15 21:11:52.050  18695-18695/lazarko.pocketformulas E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{lazarko.pocketformulas/lazarko.pocketformulas.Timeline}: android.view.InflateException: Binary XML file line #28: Error inflating class fragment
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2355)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391)
            at android.app.ActivityThread.access$600(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1335)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:155)
            at android.app.ActivityThread.main(ActivityThread.java:5520)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1029)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:796)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.view.InflateException: Binary XML file line #28: Error inflating class fragment
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:324)
            at android.app.Activity.setContentView(Activity.java:1912)
            at lazarko.pocketformulas.Timeline.onCreate(Timeline.java:35)
            at android.app.Activity.performCreate(Activity.java:5066)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1101)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2311)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391)
            at android.app.ActivityThread.access$600(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1335)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:155)
            at android.app.ActivityThread.main(ActivityThread.java:5520)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1029)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:796)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at android.support.v4.widget.DrawerLayout.isDrawerView(DrawerLayout.java:1097)
            at android.support.v4.widget.DrawerLayout.closeDrawer(DrawerLayout.java:1306)
            at lazarko.pocketformulas.NavigationDrawerFragment.selectItem(NavigationDrawerFragment.java:209)
            at lazarko.pocketformulas.NavigationDrawerFragment.onCreate(NavigationDrawerFragment.java:82)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:798)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1015)
            at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1114)
            at android.app.Activity.onCreateView(Activity.java:4722)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:680)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:324)
            at android.app.Activity.setContentView(Activity.java:1912)
            at lazarko.pocketformulas.Timeline.onCreate(Timeline.java:35)
            at android.app.Activity.performCreate(Activity.java:5066)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1101)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2311)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391)
            at android.app.ActivityThread.access$600(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1335)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:155)
            at android.app.ActivityThread.main(ActivityThread.java:5520)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1029)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:796)
            at dalvik.system.NativeStart.main(Native Method)

这是我的活动代码：

public class Timeline extends FragmentActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks, SearchView.OnQueryTextListener {
    private static NavigationDrawerFragment mNavigationDrawerFragment;
    private CharSequence mTitle;
    public static Context context;
    SearchView searchView;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_timeline);
        context = getApplicationContext();
        mNavigationDrawerFragment = (NavigationDrawerFragment)
                getFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();

        // Set up the drawer.
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));
    }
    public static Context getContext() {
        return context;
    }

    @Override
    protected void onStart() {
        super.onStart();
    }

    @Override
    protected void onResume() {
        super.onStart();
        FragmentManager fragmentManager = getSupportFragmentManager();
        SharedPreferences preferencesFragmentData = getSharedPreferences("fragmentData", 0);
        String fragmentID = preferencesFragmentData.getString("currentFragment", "");

        if(fragmentID == "FAVORITES_FRAGMENT")
            fragmentManager.beginTransaction().replace(R.id.container, new Favorites()).commit();
        else if (fragmentID == "TIMELINE_FRAGMENT")
            fragmentManager.beginTransaction().replace(R.id.container, new PlaceholderFragment()).commit();
        else if (fragmentID == "SETTINGS_FRAGMENT")
            fragmentManager.beginTransaction().replace(R.id.container, new Settings()).commit();
    }

    @Override
    protected void onPause() {
        super.onPause();
    }

    @Override
    public void onNavigationDrawerItemSelected(int position) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        SharedPreferences preferencesFragmentData = getSharedPreferences("fragmentData", 0);
        SharedPreferences.Editor editorFragmentData = preferencesFragmentData.edit();
        switch(position) {
            case 1:
                //Timeline clicked
                editorFragmentData.putString("currentFragment", "TIMELINE_FRAGMENT");
                editorFragmentData.commit();
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new PlaceholderFragment(), "TIMELINE_FRAGMENT")
                        .commit();
                break;
            case 2:
                //Favorites clicked
                editorFragmentData.putString("currentFragment", "FAVORITES_FRAGMENT");
                editorFragmentData.commit();
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new Favorites(), "FAVORITES_FRAGMENT")
                        .commit();
                break;
            case 3:
                //Settings clicked
                editorFragmentData.putString("currentFragment", "SETTINGS_FRAGMENT");
                editorFragmentData.commit();
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new Settings())
                        .commit();
                break;
            case 4:
                //Log Out clicked
                SharedPreferences loginDataPreferences = getSharedPreferences("loginData", 0);
                SharedPreferences.Editor editorLogin = loginDataPreferences.edit();
                editorLogin.putBoolean("loggedIn", false);
                editorLogin.commit();
                Intent intent = new Intent(getApplicationContext(), Login.class);
                startActivity(intent);
                break;
            default:
                editorFragmentData.putString("currentFragment", "TIMELINE_FRAGMENT");
                editorFragmentData.commit();
                fragmentManager.beginTransaction()
                        .replace(R.id.container, new PlaceholderFragment())
                        .commit();
                break;
        }

    }

    public void restoreActionBar() {
        ActionBar actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled(true);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if(!mNavigationDrawerFragment.isDrawerOpen()) {
            menu.clear();
            getMenuInflater().inflate(R.menu.timeline, menu);
            //restoreActionBar();

            searchView = new SearchView(getActionBar().getThemedContext());
            searchView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
            searchView.setQueryHint(Html.fromHtml("<font color=#FFFFFF>Search ... </font>"));
            searchView.setOnQueryTextListener(this);
            searchView.clearFocus();

            menu.add("Search").setIcon(R.drawable.ic_action_action_search).setActionView(searchView).setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM | MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW);
        }
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        return false;
    }

    //User searched for a formula and pressed Enter
    @Override
    public boolean onQueryTextSubmit(String s) {
        SharedPreferences preferencesFragmentData = getSharedPreferences("fragmentData", 0);
        String currentFragment = preferencesFragmentData.getString("currentFragment", "");

        if(currentFragment == "TIMELINE_FRAGMENT"){
            //Log.e("TIMELINE", currentFragment + "IN THE IF FRAGMENT");
            //Toast.makeText(getContext(), "You searched for: " + s + " in Timeline Fragment!", Toast.LENGTH_SHORT).show();
        } else if (currentFragment == "FAVORITES_FRAGMENT"){
            //Log.e("TIMELINE", currentFragment + "IN THE IF FRAGMENT");
            //Toast.makeText(getContext(), "You searched for: " + s + " in FAVORITES Fragment!", Toast.LENGTH_SHORT).show();
        }

        //Hide the keyboard
        InputMethodManager inputManager = (InputMethodManager) context.getSystemService(Context.INPUT_METHOD_SERVICE);
        inputManager.hideSoftInputFromWindow(this.getCurrentFocus().getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);

        invalidateOptionsMenu();

        return true;
    }

    //user started typing, this code block is for Autocomplete or Suggestions based on his current input
    @Override
    public boolean onQueryTextChange(String s) {
        return false;
    }
}

这是第一个展示的Fragment：

/**
 * Created by lazarnikolov on 11/8/14.
 */
public class PlaceholderFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    private static final String ARG_SECTION_NUMBER = "section_number";
    private static View rootView;
    FavoritesDatabaseAdapter favoritesDB;
    SwipeRefreshLayout swipeRefreshLayout = null;

    /**
     * Returns a new instance of this fragment for the given section
     * number.
     */

    public PlaceholderFragment() {
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, final ViewGroup container,
                             Bundle savedInstanceState) {
        if (rootView != null) {
            ViewGroup parent = (ViewGroup) rootView.getParent();
            if (parent != null)
                parent.removeView(rootView);
        }
        try {
            rootView = inflater.inflate(R.layout.fragment_timeline, container, false);
        } catch (InflateException e) {

        }

        favoritesDB = new FavoritesDatabaseAdapter(getActivity().getApplicationContext());
        final ContentValues contentValues = new ContentValues();

        final LinearLayout llScrollViewContainerItems = (LinearLayout) container.findViewById(R.id.llScrollViewContainerItems);
        llScrollViewContainerItems.removeAllViews();
        ActionBar actionBar = getActivity().getActionBar();
        final Typeface font = Typeface.createFromAsset(getActivity().getAssets(), "ubuntu.ttf");
        actionBar.setBackgroundDrawable(new ColorDrawable(getResources().getColor(R.color.PeterRiver)));
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setTitle("Timeline");

        swipeRefreshLayout = (SwipeRefreshLayout) container.findViewById(R.id.container);

        swipeRefreshLayout.setColorSchemeResources(R.color.Alizarin, R.color.Emerald, R.color.PeterRiver, R.color.Amethyst, R.color.WetAsphalt);
        swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {...}
        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

    }

    @Override
    public void onStop() {
        super.onStop();
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        Fragment f = (Fragment) getFragmentManager()
                .findFragmentByTag("TIMELINE_FRAGMENT");
        if (f != null)
            getFragmentManager().beginTransaction().remove(f).commit();
    }
}

这是我的activity_timeline.xml文件，错误发生在这里：

<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:id="@+id/drawer_layout"
    android:layout_width="match_parent" android:layout_height="match_parent"
    tools:context=".Timeline">

    <!-- As the main content view, the view below consumes the entire
         space available using match_parent in both dimensions. -->
    <android.support.v4.widget.SwipeRefreshLayout android:id="@+id/container" android:layout_width="match_parent"
        android:layout_height="match_parent" android:orientation="vertical">
        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/svContainerViews">
            <LinearLayout android:id="@+id/llScrollViewContainerItems" android:layout_width="match_parent"
                android:layout_height="match_parent" android:orientation="vertical">
            </LinearLayout>
        </ScrollView>
    </android.support.v4.widget.SwipeRefreshLayout>

    <!-- android:layout_gravity="start" tells DrawerLayout to treat
         this as a sliding drawer on the left side for left-to-right
         languages and on the right side for right-to-left languages.
         If you're not building against API 17 or higher, use
         android:layout_gravity="left" instead. -->
    <!-- The drawer is given a fixed width in dp and extends the full height of
         the container. -->
    <fragment android:id="@+id/navigation_drawer"
        android:layout_width="@dimen/navigation_drawer_width" android:layout_height="match_parent"
        android:layout_gravity="start"
        android:name="lazarko.pocketformulas.NavigationDrawerFragment"
        tools:layout="@layout/fragment_navigation_drawer" />

</android.support.v4.widget.DrawerLayout>

我的登录活动类：

/**
 * Created by lazarnikolov on 11/8/14.
 */
public class Login extends Activity{
    EditText etEmail, etPassword;
    Button bLogin, bRegister;
    Typeface font;
    TextView tvLogIn;

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        SharedPreferences preferences = getSharedPreferences("loginData", 0);
        boolean loggedIn = preferences.getBoolean("loggedIn", false);

        if(loggedIn) {
            Intent intent = new Intent("android.intent.action.TIMELINE");
            startActivity(intent);
        }
        SharedPreferences initialFragmentData = getSharedPreferences("fragmentData", 0);
        SharedPreferences.Editor initialEditorFragmentData = initialFragmentData.edit();
        initialEditorFragmentData.putString("currentFragment", "TIMELINE_FRAGMENT");
        initialEditorFragmentData.commit();

        setContentView(R.layout.login);
        font = Typeface.createFromAsset(getAssets(), "ubuntu.ttf");

        etEmail = (EditText) findViewById(R.id.etEmail);
        etEmail.setTypeface(font);
        etPassword = (EditText) findViewById(R.id.etPassword);
        etPassword.setTypeface(font);
        tvLogIn = (TextView) findViewById(R.id.tvRegister);
        tvLogIn.setTypeface(font);
        bLogin = (Button) findViewById(R.id.bLogin);
        bLogin.setTypeface(font);

        bLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SharedPreferences preferences = getSharedPreferences("loginData", 0);
                SharedPreferences.Editor editor = preferences.edit();
                editor.putBoolean("loggedIn", true);
                editor.commit();
                communicate();
                Intent intent = new Intent("android.intent.action.TIMELINE");
                //intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent);
            }
        });

        bRegister = (Button) findViewById(R.id.bRegister);
        bRegister.setTypeface(font);
        bRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent("android.intent.action.REGISTER");
                startActivity(intent);
            }
        });
    }

    //    SERVER COMMUNICATION CLASS INITIALIZATION
    private void communicate() {
        new GetData().execute();
    }

    //    SERVER COMMUNICATION CLASS
    private class GetData extends AsyncTask<Void, Void, String> {
        @Override
        protected String doInBackground(Void... voids) {
            Looper.prepare();
            String data = "";
            InputStream inputStream = null;
            try {
                HttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost("*******");

                String json = "";
                JSONObject object = new JSONObject();
                object.accumulate("email", etEmail.getText().toString());
                object.accumulate("password", etPassword.getText().toString());
                json = object.toString();
                StringEntity se = new StringEntity(json);
                httpPost.setEntity(se);
                httpPost.setHeader("Accept", "application/json");
                httpPost.setHeader("Content-type", "application/json");
                HttpResponse response = httpClient.execute(httpPost);
                inputStream = response.getEntity().getContent();
                if(inputStream != null){
                    Toast.makeText(getApplicationContext(), "Logged in!", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(getApplicationContext(), "Invalid username/password", Toast.LENGTH_SHORT).show();
                }

            } catch(Exception e) {
                Log.e("log_tag", "Error in http connection: " + e.toString());
            }
            return data;
        }

        @Override
        protected void onPostExecute(String result) {
            //Toast.makeText(getApplicationContext(), result, Toast.LENGTH_LONG).show();
        }
    }

    @Override onStart(), onRestart(), onResume()...
}

我已经搜索了很长时间，但仍然找不到解决方案。请看一下并告诉我你认为问题是什么！

非常感谢！

- Lazar Nikolov

Answer 1

仔细查看/调试 lazarko.pocketformulas.NavigationDrawerFragment.java 的第209行（它属于selectItem()方法）
根据您的堆栈跟踪，可能存在一个空的或没有正确初始化的对象

更新 为了找到为什么有时会发生，有时不会发生的原因（如果我理解正确），还需要提出更多问题。
1）当您在一段时间后启动活动时是否会发生？如果是，那么可能与系统释放资源并重新创建活动有关

2）如果不是-您必须逐步移动以找到原因。跟踪对象何时被设为空值。可能是：
-- 在父对象重新创建时（未正确初始化时）
-- 在其类内部（只需使用ctrl+f查找所有出现）
-- 在其类外部。请将对象设置为private并声明setter方法来跟踪它

- sberezin

---

是的，我知道它是一个Null，并且我知道它在我的Timeline类的onCreate方法中的setContentView(R.layout.activity_timeline)。但我不知道为什么会发生这种情况。就像我上面写的那样，我进入那个活动，一切看起来都很好，很正常，但当我退出并稍后再次尝试进入时，它会在setContentView上抛出NullPointerException... - Lazar Nikolov

没有看到，我启动应用程序，登录活动是第一个，但它被绕过了，因为我设置了一条规则，如果您已经登录，则不应显示登录屏幕。绕过后出现时间轴屏幕。一切看起来都很好，没有错误也没有崩溃。然后我点击注销按钮，它会带我到登录屏幕。同样，没有错误也没有崩溃。之后，我点击登录按钮以进入时间轴屏幕。这就是崩溃发生的时候。当我两次访问时间轴活动时。时间轴>登录>时间轴。 - Lazar Nikolov

抱歉，我没有确切的答案。但如果它是 null（之前不是 null），则必须存在一个将其设为 null 的地方！请参见更新 2）。通常原因很简单，你只需要找到它。 - sberezin

Answer 2

好的，我已经修复了这个bug。我一直在使用错误的intent标识。这是修复方法：

intent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);

我将这段代码插入到时间轴活动的开始位置和“退出登录”按钮上。现在，我在setContentView上不再遇到NullPointerException错误。

- Lazar Nikolov