FragmentList的ArrayAdapter使应用程序崩溃

如何解决FragmentList的ArrayAdapter使应用程序崩溃

| 这是我的Android应用程序代码：

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    //Attempting to set the Fragment
    System.err.println(\"Starting\");
    FragmentManager fm = getFragmentManager();
    FragmentTransaction ft = fm.beginTransaction();
    System.err.println(\"Adding the fragment\");
    Filebrowser fb = new Filebrowser();
    ft.add(R.id.flFbrowser,fb);
    ft.commit();
    System.err.println(\"Done\");

    fb.test();
}

文件浏览器仅具有以下功能：

public void test(){
    System.err.println(\"Entre a test!!!\");
    String[] MyList = {\"Hello\",\"world\",\"of\",\"the\",\"lists\"};
    System.err.println(\"File Row ID\" + Integer.toString(R.layout.file_row));
    ArrayAdapter<String> aa = new ArrayAdapter<String>(getActivity(),R.layout.file_row,MyList);
    //setlistadapter(aa);       
}

问题是，如果我注释ArrayAdapter构造函数，则程序不会崩溃。如果我取消注释，它将崩溃并显示以下错误：

06-11 10:12:38.150: ERROR/AndroidRuntime(4804): FATAL EXCEPTION: main
06-11 10:12:38.150: ERROR/AndroidRuntime(4804): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ccr/com.ccr.Main}: java.lang.NullPointerException
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:1748)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1764)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.app.ActivityThread.access$1500(ActivityThread.java:122)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1002)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.os.Looper.loop(Looper.java:132)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.app.ActivityThread.main(ActivityThread.java:4025)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at java.lang.reflect.Method.invokeNative(Native Method)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at java.lang.reflect.Method.invoke(Method.java:491)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at dalvik.system.NativeStart.main(Native Method)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804): Caused by: java.lang.NullPointerException
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.widget.ArrayAdapter.init(ArrayAdapter.java:314)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:128)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at com.ccr.Filebrowser.test(Filebrowser.java:13)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at com.ccr.Main.onCreate(Main.java:24)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:1712)
06-11 10:12:38.150: ERROR/AndroidRuntime(4804):     ... 11 more

有人知道我可能做错了什么吗？谢谢你的帮助！更新：问题似乎特别是getActivity返回null？知道为什么会这样吗？