AppCompatActivity 中的片段
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【中文标题】AppCompatActivity 中的片段【英文标题】：Fragments in AppCompatActivity 【发布时间】：2017-04-26 00:10:16 【问题描述】：如果我想在我的滑动视图活动中使用 Fragments，我可以使用这个扩展吗？
public class Overview_Screen extends AppCompatActivity
我的 Fragment 类使用这个：
public class MessagesFragmentPortrait extends android.support.v4.app.Fragment
我问这个是因为我的应用程序不断崩溃... 这是我的主要活动：
public class Overview_Screen extends AppCompatActivity
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_overview_screen);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
@Override
public boolean onCreateOptionsMenu(Menu menu)
getMenuInflater().inflate(R.menu.menu_overview_screen, menu);
return true;
@Override
public boolean onOptionsItemSelected(MenuItem item)
int id = item.getItemId();
if (id == R.id.action_settings)
Intent settings_intent = new Intent(this, Settings_Screen.class);
startActivity(settings_intent);
return true;
return super.onOptionsItemSelected(item);
public static class SectionsPagerAdapter extends FragmentPagerAdapter
public SectionsPagerAdapter(FragmentManager fm)
super(fm);
@Override
public Fragment getItem(int i)
switch (i)
case 0:
return new AccountFragmentPortrait();
case 1:
return new FeedFragmentPortrait();
default:
return new MessagesFragmentPortrait();
@Override
public int getCount()
return 3;
@Override
public CharSequence getPageTitle(int position)
switch (position)
case 0:
return "Account";
case 1:
return "Feed";
case 2:
return "Messages";
return null;
这是我的堆栈跟踪：
FATAL EXCEPTION: main
Process: de.lukas_schroederoutlook.connect, PID: 3364
java.lang.RuntimeException: Unable to start activity ComponentInfode.lukas_schroederoutlook.connect/de.lukas_schroederoutlook.connect.Overview_Screen:
android.view.InflateException: Binary XML file line #41: Binary XML file line #41: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: android.view.InflateException: Binary XML file line #41: Binary XML file line #41: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #41: Error inflating class fragment
Caused by: java.lang.NullPointerException
at java.lang.VMClassLoader.findLoadedClass(Native Method)
at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:742)
at java.lang.ClassLoader.loadClass(ClassLoader.java:362)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at android.support.v4.app.Fragment.isSupportFragmentClass(Fragment.java:469)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2384)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:120)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:378)
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:33)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:77)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:777)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:858)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
at android.view.LayoutInflater.inflate(LayoutInflater.java:377)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:284)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:143)
at de.lukas_schroederoutlook.connect.Overview_Screen.onCreate(Overview_Screen.java:42)
at android.app.Activity.performCreate(Activity.java:6679)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
最后，这是我的概览屏幕 xml：
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_content"
android:layout_
android:layout_
android:fitsSystemWindows="true"
tools:context="de.lukas_schroederoutlook.connect.Overview_Screen">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_
android:layout_
android:paddingTop="@dimen/appbar_padding_top"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_
android:layout_
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/AppTheme.PopupOverlay">
</android.support.v7.widget.Toolbar>
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
android:layout_
android:layout_ />
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/container"
android:layout_
android:layout_
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
<fragment
android:layout_
android:layout_
android:id="@+id/feed_fragment_portrait"/>
<fragment
android:layout_
android:layout_
android:id="@+id/feed_fragment_landscape"/>
还有我的概览屏幕片段 xml：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="de.lukas_schroederoutlook.connect.Overview_Screen$PlaceholderFragment">
<TextView
android:id="@+id/section_label"
android:layout_
android:layout_ />
【问题讨论】：
请分享您使用的代码并写下错误代码 你有一个错误 de.lukas_schroederoutlook.connect/de.lukas_schroederoutlook.connect.Overview_Screen xml 端。请分享这个xml代码 【参考方案1】：您需要在<fragment> 标签中指定class 属性。
<fragment
android:layout_
android:layout_
android:id="@+id/feed_fragment_portrait"/>
<fragment
android:layout_
android:layout_
android:id="@+id/feed_fragment_landscape"/>
在这两者上添加class="your.packagename.SomeFragment"（如果你真的需要两者...通常你有不同的布局文件用于土地空间和肖像，而不是两者合二为一）
看起来您使用的是 ViewPager，那么您真的需要 <fragment> 标记吗？我认为您可以删除它们。
【讨论】：
【参考方案2】：你需要这样的东西：
<fragment
android:name="de.lukas_schroederoutlook.connect.FeedFragmentPortrait"
android:layout_
android:layout_
android:id="@+id/feed_fragment_portrait"/>
或者使用
class=
正如板球所说。
【讨论】：
这表示你可以使用 "name=..." developer.android.com/guide/components/fragments.html 这里说“name=”和“class=”是一样的。 ***.com/questions/10162983/… 我在发布之前查看了我的一个项目，它使用“name="，我认为这是当时唯一的方法。以上是关于AppCompatActivity 中的片段的主要内容，如果未能解决你的问题，请参考以下文章
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