Java 在android中测试，片段上的NullPointerException

试图在我的Android应用程序中实现一些小测试用例，但目前我在让测试类找到片段方面遇到了一些困难

public class DetailActivity extends FragmentActivity {

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_detail);
       Intent intent = getIntent();
       Bundle bundle = new Bundle();
       bundle.putParcelable("match", intent.getParcelableExtra("match"));
       DetailFragment fragment = new DetailFragment();
       fragment.setArguments(bundle);
       if (savedInstanceState == null) {
          getSupportFragmentManager().beginTransaction()
                  .add(R.id.container, fragment, "test")
                  .commit();
       }
   }
}

这是我的活动，它只是创建了我的片段

public class DetailActivity extends FragmentActivity {

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_detail);
       Intent intent = getIntent();
       Bundle bundle = new Bundle();
       bundle.putParcelable("match", intent.getParcelableExtra("match"));
       DetailFragment fragment = new DetailFragment();
       fragment.setArguments(bundle);
       if (savedInstanceState == null) {
          getSupportFragmentManager().beginTransaction()
                  .add(R.id.container, fragment, "test")
                  .commit();
       }
   }
}

我的碎片看起来像这样

public class DetailFragment extends Fragment {
   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

      context = getActivity().getApplicationContext();
      mh = getArguments().getParcelable("match");

      int id = context.getResources().getIdentifier(
              "c" + String.valueOf(mh.getChampionImage()),
              "drawable", context.getPackageName()
      );
    }

    @Override
    public void onStart() {
      super.onStart();
      if (Utility.hasNetworkConnection(context)) {
         FetchIcons fetchIcons = new FetchIcons();
         fetchIcons.execute(mh);
      }
    }

...//Some Code

public class DetailFragmentTest extends ActivityUnitTestCase<DetailActivity> {

   DetailActivity activity;
   DetailFragment fragment;

   public DetailFragmentTest() {
       super(DetailActivity.class);
   }

   @Override
   protected void setUp() throws Exception {
      super.setUp();
      Intent intent = new Intent(new MockContext(), DetailActivity.class);
      int[] i = {1, 2, 3, 4, 5, 6, 7};
      MatchHistory mh = new MatchHistory("Win", "23", "42", "31", "23414", "321", 22, true, i);
      intent.putExtra("match", mh);
      startActivity(intent, null, null);
      activity = getActivity();
      fragment = (DetailFragment) activity.getSupportFragmentManager().findFragmentByTag("test");

   }

   public void testText() {
    ...//Some more code
   }
}

我的测试是这样的

public class DetailFragment extends Fragment {
   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

      context = getActivity().getApplicationContext();
      mh = getArguments().getParcelable("match");

      int id = context.getResources().getIdentifier(
              "c" + String.valueOf(mh.getChampionImage()),
              "drawable", context.getPackageName()
      );
    }

    @Override
    public void onStart() {
      super.onStart();
      if (Utility.hasNetworkConnection(context)) {
         FetchIcons fetchIcons = new FetchIcons();
         fetchIcons.execute(mh);
      }
    }

...//Some Code

public class DetailFragmentTest extends ActivityUnitTestCase<DetailActivity> {

   DetailActivity activity;
   DetailFragment fragment;

   public DetailFragmentTest() {
       super(DetailActivity.class);
   }

   @Override
   protected void setUp() throws Exception {
      super.setUp();
      Intent intent = new Intent(new MockContext(), DetailActivity.class);
      int[] i = {1, 2, 3, 4, 5, 6, 7};
      MatchHistory mh = new MatchHistory("Win", "23", "42", "31", "23414", "321", 22, true, i);
      intent.putExtra("match", mh);
      startActivity(intent, null, null);
      activity = getActivity();
      fragment = (DetailFragment) activity.getSupportFragmentManager().findFragmentByTag("test");

   }

   public void testText() {
    ...//Some more code
   }
}

我一直在尝试使用几种不同的方法来解决这个问题，包括ActivityInstrumentationTestCase2，但是我甚至无法获得Activity

我显然做错了什么。但是，由于安卓系统中没有一个单元测试教程能带来好运，我至少可以在这里试一试，看看是否有人知道问题出在哪里

---

问候

碎片被惰性地附着。这意味着您必须调用“executePendingTransactions”，如

---

什么是

DetailFragmentTest.java:34

？也许您可以调用

getActivity（）太早了，它返回空值。是的，我猜是我的错。java:34指的是我试图获取片段的那一行。我想类似的事情也会发生，但尝试运行activity.getSupportManager也会导致NullPointerException。所以我想问题在于返回的活动，而不是片段。但是assertnotnull通过了测试，这很奇怪。类似的问题可能会有所帮助