Question

我正在使用包含三个标签的FragmentTabHost。我在第一个选项卡的onCreateView中得到一个空指针异常，我正在尝试添加一个webViewClient ..我是android的新手，我无法弄清楚代码有什么问题......

我以前在我的主布局文件中有一个侧边栏/汉堡包抽屉，但是只要我从我的activity_lest_see_main xml文件中删除它..我开始在Tab1Activity中获取NullPointerException ..请帮助..我真的被困在这个问题。只要我在我的lest_see_main.xml文件中添加侧边栏/汉堡包抽屉，代码就会开始运行而不会出现任何错误，并且应用程序正常运行。

我始终在NullPointerException mwebView.setWebViewClient(new HelloWebViewClient)处获得Tab1Activity。

这是我在Logcat中得到的以及顶部的NullPointerException -

07-28 18:24:52.735: E/AndroidRuntime(6834): FATAL EXCEPTION: main
07-28 18:24:52.735: E/AndroidRuntime(6834): java.lang.NullPointerException
07-28 18:24:52.735: E/AndroidRuntime(6834):     at com.example.itslive.Tab1Activity.onCreateView(Tab1Activity.java:168)
07-28 18:24:52.735: E/AndroidRuntime(6834):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
07-28 14:17:31.274: E/AndroidRuntime(29029):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
07-28 14:17:31.274: E/AndroidRuntime(29029):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
07-28 14:17:31.274: E/AndroidRuntime(29029):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
07-28 14:17:31.274: E/AndroidRuntime(29029):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)

这是我的主要Activity的xml文件，它扩展了Fragment Activity

activity_lest_see_main.xml

<RelativeLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/rev"
 android:layout_width="match_parent"
 android:layout_height = "match_parent"
 android:layout_gravity="start">

<RelativeLayout
 android:id="@+id/mainContent"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 >
 <android.support.v4.app.FragmentTabHost
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:id="@android:id/tabhost">

  <LinearLayout 
   android:id="@+id/LinearLayout01"
   android:orientation="vertical" 
   android:layout_height="fill_parent"
   android:layout_width="fill_parent">

   <TabWidget 
    android:id="@android:id/tabs"
    android:layout_height="wrap_content" 
    android:layout_width="fill_parent">
    </TabWidget>

    <FrameLayout 
     android:id="@android:id/tabcontent"
     android:layout_height="fill_parent"
     android:layout_width="fill_parent">
     </FrameLayout>

    </LinearLayout>

    </android.support.v4.app.FragmentTabHost> 

    <Button
     android:id="@+id/exit"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:background="@android:color/transparent"
     android:layout_gravity="bottom"
     android:layout_alignParentBottom="true"
     android:text = "@string/exit_button"
     android:textColor="@color/blue"
     android:textSize="20sp"
     android:layout_centerHorizontal="true"/>

     </RelativeLayout>


     </RelativeLayout>

这是扩展Fragmentactivity的MainActivity java文件

LetsSeeMainActivity.java

public class LestSeeMainActivity extends FragmentActivity  {
private FragmentTabHost tabHost;
int flag = 0;
int n;
private static final String TAG = "LetsSeeMainActivity";
private AudioManager maudioManager;
Fragment mContent;


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


    setContentView(R.layout.activity_lest_see_main);


        maudioManager = (AudioManager) getSystemService(AUDIO_SERVICE);

    final Button exitb = (Button)findViewById(R.id.exit);

    exitb.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            maudioManager.playSoundEffect(AudioManager.FX_KEY_CLICK);
            finish();
        }
    });


    tabHost = (FragmentTabHost) findViewById(android.R.id.tabhost);
    tabHost.setup(this, getSupportFragmentManager(), android.R.id.tabcontent);

     tabHost.addTab(
                tabHost.newTabSpec("tab1").setIndicator("Tab1", null),
                Tab1Activity.class, null);
        tabHost.addTab(
                tabHost.newTabSpec("tab2").setIndicator("Tab2", null),
                Tab2Activity.class, null);
        tabHost.addTab(
                tabHost.newTabSpec("tab3").setIndicator("Tab3", null),
                Tab3Activity.class, null);  
}

}

这是我的第一个Fragment Activity java文件的onCreateView

Tab1Activity.java

public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
}

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    if(v==null)
    {
    v = inflater.inflate(R.layout.activity_tab1, container, false);
     mwebView = (WebView) v.findViewById(R.id.wb1);
     mwebView.setWebViewClient(new HelloWebViewClient());
     registerForContextMenu(mwebView);

    }

这是我的activity_tab1.xml文件 -

  <android.support.v4.widget.SwipeRefreshLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/swipe_refresh_layout"
  android:layout_width="match_parent"
  android:layout_height="match_parent">

 <WebView android:id="@+id/wb1" 
 android:layout_width="match_parent"
 android:layout_height="wrap_content" /> 

 <ProgressBar
 android:id="@+id/progressBar1"
 style="?android:attr/progressBarStyleHorizontal"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:maxHeight="5dp"
 android:minHeight="5dp"
 android:visibility="invisible"
 />

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

Answer 1

尝试放

mwebView = (WebView) v.findViewById(R.id.wb1);
mwebView.setWebViewClient(new HelloWebViewClient());
registerForContextMenu(mwebView);

onViewCreated（..）中的

。

使用FragmentTabHost在onCreateView中出现空指针异常

1 个答案: