如何将此活动转换为片段？

Question

我正在开发我的第一个应用程序，我的 Activity 中有以下代码，现在我想将其转换为 Fragment（以使用选项卡式 Activity）；

public class StatTab1 extends Activity {

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.stattab1);

        ListView lview = (ListView) findViewById(R.id.listview);
        populateList();
        ListViewAdapter adapter = new ListViewAdapter(this, list);
        lview.setAdapter(adapter);
    }
...

我是这样改代码的：

public class StatTab1 extends Fragment {

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ListView lview = (ListView) getView().findViewById(R.id.listview);
        populateList();
        ListViewAdapter adapter = new ListViewAdapter(getActivity(), list);
        lview.setAdapter(adapter);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {             
        View rootView = inflater.inflate(R.layout.stattab1, container, false);
        return rootView;
    }
    ...

我收到此错误：java.lang.RuntimeException: Unable to start activity ComponentInfo java.lang.NullPointerException。

这里是 LogCat：

10-03 21:10:30.915: E/AndroidRuntime(18005): FATAL EXCEPTION: main
10-03 21:10:30.915: E/AndroidRuntime(18005): Process: com.example.myapp, PID: 18005
10-03 21:10:30.915: E/AndroidRuntime(18005): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapp/com.example.myapp.Stats}: java.lang.NullPointerException
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2212)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.ActivityThread.access$800(ActivityThread.java:144)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.os.Handler.dispatchMessage(Handler.java:102)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.os.Looper.loop(Looper.java:136)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.ActivityThread.main(ActivityThread.java:5146)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at java.lang.reflect.Method.invokeNative(Native Method)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at java.lang.reflect.Method.invoke(Method.java:515)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at dalvik.system.NativeStart.main(Native Method)
10-03 21:10:30.915: E/AndroidRuntime(18005): Caused by: java.lang.NullPointerException
10-03 21:10:30.915: E/AndroidRuntime(18005):    at com.example.myapp.StatTab1.onCreate(StatTab1.java:31)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.Fragment.performCreate(Fragment.java:1678)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:859)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.BackStackRecord.run(BackStackRecord.java:684)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.Activity.performStart(Activity.java:5240)
10-03 21:10:30.915: E/AndroidRuntime(18005):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2178)
10-03 21:10:30.915: E/AndroidRuntime(18005):    ... 11 more

Answer 1

我终于弄清楚了问题并解决了。这可以解决问题：

public class StatTab1 extends Fragment
{    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {             
        View rootView = inflater.inflate(R.layout.stattab1, container, false);

        ListView lview = (ListView) rootView.findViewById(R.id.listview);
        populateList();
        ListViewAdapter adapter = new ListViewAdapter(getActivity(), list);
        lview.setAdapter(adapter);

        return rootView;
    }
...