Android阵列适配器出错

Question

我正在尝试使用一个充满对象的arrayadapter来填充listview，但是当我尝试将适配器插入列表视图时，我得到了一个java.lang.nullPointException。有人能帮帮我吗？

这是我使用的方法..请帮助

public class MyListFragment extends Fragment  {
DataManager dm;  


  private OnItemSelectedListener listener;


  public void populateListView(Context contexts)
  { 
      dm = DataManager.getInstance(contexts);
      Log.i("IS4432","OPen");
      dm.open();

      Log.i("IS4432","OPen");
    Store RI = new Store("River Island","Clothing Store","Cork", "45664", R.drawable.ic_launcher);
    Store NL = new Store("New Look","Clothing Store","Cork", "45664", R.drawable.ic_launcher);
    Store HM = new Store("H&M","Clothing Store","Cork", "45664", R.drawable.ic_launcher);
    Store TS = new Store("Top Shop","Clothing Store","Cork", "45664", R.drawable.ic_launcher);

    int newId1 = dm.add(RI);
    int newId2 = dm.add(NL);
    int newId3 = dm.add(HM);
    int newId4 = dm.add(TS);

    Log.i("IS4432",String.valueOf(newId1));
    Log.i("IS4432",String.valueOf(newId2));
    Log.i("IS4432",String.valueOf(newId3));
    Log.i("IS4432",String.valueOf(newId4));


    List<Store> allUsers = dm.getAll(Store.class);

     ArrayAdapter<Store> adapter = new ArrayAdapter<Store>(contexts, android.R.layout.simple_list_item_1, allUsers);

    //set adapter
    ListView mylist = (ListView) view.findViewById(R.id.listViewFromDb);

//This is where my problem is     
      try
      {
    mylist.setAdapter(adapter);
              }
      catch(Exception ee)
      {           
          Log.i("Error",ee.toString());
    }
      Log.i("IS4432","OPen4ghkgkh");


    dm.close(); 
    }