Android Dagger2依賴注入CustomAdapter

Question

我學習依賴注入在我的android代碼中使用Dagger2，我沒有任何麻煩，直到我嘗試注入演示者在我的CustomAdapter ListView中，它總是返回空值。目的是當有人點擊ListView項目時，我想執行Presenter功能。這是我CustomAdapter樣子：

public class CustomAdapter extends BaseAdapter { 

ArrayList<String> contactNameList, listGroup; 
Context context; 
ArrayList<Bitmap> contactImages; 
ArrayList<Integer> listContactId; 

private static LayoutInflater inflater=null; 

@Inject 
DetailScreenPresenter detailScreenPresenter; 

public CustomAdapter(MainActivity mainActivity, ArrayList<String> contactNameList, ArrayList<Bitmap> contactImages, ArrayList<String> listGroup, ArrayList<Integer> listContactId) 
{ 
    this.contactNameList = contactNameList; 
    context = mainActivity; 
    this.contactImages = contactImages; 
    this.listGroup = listGroup; 
    this.listContactId = listContactId; 
    inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
} 

@Override 
public int getCount() { 
    return contactNameList.size(); 
} 

@Override 
public Object getItem(int position) { 
    return position; 
} 

@Override 
public long getItemId(int position) { 
    return position; 
} 

public static class Holder 
{ 

    public Holder(View view,Context context) 
    { 
     ButterKnife.bind(this,view); 

    } 

    @BindView(R.id.txtName) 
    TextView tvName; 

    @BindView(R.id.txtGroup) 
    TextView tvGroup; 

    @BindView(R.id.imageProfile) 
    ImageView img; 
} 

@Override 
public View getView(final int position, View convertView, ViewGroup parent) { 

    View rowView; 
    rowView = inflater.inflate(R.layout.contact_list, null); 
    Holder holder=new Holder(rowView, context); 

    holder.tvName.setText(contactNameList.get(position)); 
    holder.img.setImageBitmap(contactImages.get(position)); 
    holder.tvGroup.setText(listGroup.get(position)); 
    rowView.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      detailScreenPresenter.loadDetail(listContactId.get(position)); 
     } 
    }); 
    return rowView; 
} 
} 

，這是觸發CustomAdapter

public class MainActivity extends AppCompatActivity implements MainScreenContact.View { 

@BindView(R.id.listContact) 
ListView listView; 

ArrayList<String> listName; 
ArrayList<Bitmap> listImage; 
ArrayList<String> listGroup; 
ArrayList<Integer> listContactId; 
HashMap<Integer, Bitmap> tempImageArray; 
String[] letter={"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"}; 


@Inject 
MainScreenPresenter mainPresenter; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    ButterKnife.bind(this); 

    listName = new ArrayList<>(); 
    listImage = new ArrayList<>(); 
    tempImageArray = new HashMap<>(); 
    listGroup = new ArrayList<>(); 
    listContactId = new ArrayList<>(); 

    DaggerMainScreenComponent.builder() 
      .netComponent(((App) getApplicationContext()).getNetComponent()) 
      .mainScreenModule(new MainScreenModule(this, new ContactDatabaseHelper(this))) 
      .build().inject(this); 

    mainPresenter.loadPost(); 
} 


@Override 
public void showPosts(List<Post> posts) { 

    Collections.sort(posts, new Comparator<Post>() { 
     @Override 
     public int compare(Post post1, Post post2) { 
      String name1=post1.getFirstName()+" "+post1.getLastName(); 
      String name2=post2.getFirstName()+" "+post2.getLastName(); 
      return name1.compareToIgnoreCase(name2); 
     } 
    }); 

    int indexGroup=0; 

    for (int i = 0; i < posts.size(); i++) { 

     if(posts.get(i).getProfilePic().contains("http")) 
      mainPresenter.loadImage(posts.get(i).getProfilePic(), i); 
     else 
      mainPresenter.loadImage("http://example.com", i); 


     if(Arrays.binarySearch(letter,Character.toString(posts.get(i).getFirstName().charAt(0)).toUpperCase())==-1) 
     { 
      if(listGroup.size()==0) 
       listGroup.add("*"); 
      else 
       listGroup.add(" "); 
     } 
     else 
     { 
      if(!listGroup.get(indexGroup).equalsIgnoreCase(Character.toString(posts.get(i).getFirstName().charAt(0)))) { 
       listGroup.add(Character.toString(posts.get(i).getFirstName().charAt(0)).toUpperCase()); 
       indexGroup = i; 
      } 
      else 
       listGroup.add(" "); 
     } 

     listContactId.add(i, posts.get(i).getId()); 
     listName.add(i, posts.get(i).getFirstName() + " " + posts.get(i).getLastName()); 

    } 

} 


@Override 
public void showError(String message) { 
    Toast.makeText(getApplicationContext(), "Error" + message, Toast.LENGTH_LONG).show(); 
} 

@Override 
public void showComplete() { 
    Toast.makeText(getApplicationContext(), "Complete", Toast.LENGTH_LONG).show(); 
} 

@Override 
public void setImageProfile(Bitmap profileBmp, int x) { 
    tempImageArray.put(x, profileBmp); 

    if(tempImageArray.size()==listName.size()) 
    { 

     SortedSet<Integer> keys = new TreeSet<Integer>(tempImageArray.keySet()); 
     for(Integer key : keys) 
     { 
      listImage.add(tempImageArray.get(key)); 
     } 

     listView.setAdapter(new CustomAdapter(this, listName, listImage, listGroup, listContactId)); 
    } 

} 
} 

請幫助如何注入DetailScreenPresenter主持人在MainActivity。

非常感謝

Answer 1

一般情況下，爲了執行注射到任何對象，你應該明確地調用<some_dagger_component>.inject(<target_object>)。

在你的情況，你可以這樣來做：

CustomAdapter adapter = new CustomAdapter(this, listName, listImage, listGroup, listContactId); 

DaggerMainScreenComponent.builder() 
      .netComponent(((App) getApplicationContext()).getNetComponent()) 
      .mainScreenModule(new MainScreenModule(this, new ContactDatabaseHelper(this))) 
      .build().inject(adapter); 

listView.setAdapter(adapter); 

但是，你正在做的是依賴注入框架的濫用 - 你不應該進行注入適配器，但只需通過所需的對象適配器的構造函數。

在this post中，您可以在Android中找到有關依賴注入的其他信息。