Android 2.3自定义ArrayAdapter getView方法不被称为

Question

编辑：解决...主要。调用LOD.g（...）在getView（）中仍然没有出现在LogCat中，但似乎一切正常。下面的代码已更新为工作版本。

我一个ArrayAdapter类：

public class PostAdapter extends ArrayAdapter<Post> { 

//fields 
private LayoutInflater inflater; 
private ArrayList<Post> posts; 

//constructor 
public PostAdapter(Context context, ArrayList<Post> posts) { 
    super(context, R.layout.post_layout, R.id.title, posts); 
    this.inflater = LayoutInflater.from(context); 
    this.posts = posts; 
} 

//methods 
@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
    //get data item for this position 
    Post post = (Post)getItem(position); 
    //check if existing view is being reused, otherwise inflate the view 
    if(convertView == null) { 
     convertView = inflater.inflate(R.layout.post_layout, parent, false); 
    } 
    //Populate views with data 
    TextView title = (TextView) convertView.findViewById(R.id.title); 
    title.setText(post.getTitle()); 
    TextView subTitle = (TextView) convertView.findViewById(R.id.subTitle); 
    subTitle.setText(post.getDescription()); 

    //return completed view to render on screen 
    return convertView; 
} 

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

}

和代码，我创建一个ArrayAdapter：

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

    //Initializing feed variables 
    posts = new ArrayList<>(); 
    postAdapter = new PostAdapter(this, posts); 
    list = (ListView) findViewById(R.id.list); 

    //attaching Adapter to ListView 
    list.setAdapter(postAdapter); 

    DatabaseReference p = database.getReference("posts"); 
    p.addChildEventListener(new ChildEventListener() { 
     @Override 
     public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
      //get reference to post 
      HashMap<Object, Object> entry = (HashMap<Object, Object>) dataSnapshot.getValue(); 

      //convert to Post.class datatype 
      Post post = new Post(); 
      if (entry.get("category") != null) { post.setCategory(entry.get("category").toString()); } 
      if (entry.get("title") != null) { post.setTitle(entry.get("title").toString()); } 
      if (entry.get("description") != null) { post.setDescription(entry.get("description").toString()); } 
      if (entry.get("hasImg") != null) { post.setImg((boolean)entry.get("hasImg")); } 
      if (entry.get("postKey") != null) { post.setPostKey(entry.get("postKey").toString()); } 
      if (entry.get("posterID") != null) { post.setPosterID(entry.get("posterID").toString()); } 
      if (entry.get("schoolID") != null) { post.setSchoolID(entry.get("schoolID").toString()); } 
      if (entry.get("flagged") != null) { post.setFlagged((long)entry.get("flagged")); } 
      if (entry.get("time") != null) { post.setTime((long)entry.get("time")); }; 

      //add to ArrayList 
      posts.add(post); 
      postAdapter.notifyDataSetChanged(); 

      Log.d("LIST", "Post Added: Posts: " + postAdapter.getCount()); 
     } 

     @Override 
     public void onChildChanged(DataSnapshot dataSnapshot, String s) { 

     } 

     @Override 
     public void onChildRemoved(DataSnapshot dataSnapshot) { 

     } 

     @Override 
     public void onChildMoved(DataSnapshot dataSnapshot, String s) { 

     } 

     @Override 
     public void onCancelled(DatabaseError databaseError) { 

     } 
    }); 
} 

Answer 1

#List adapter is getting initialized with zero posts elements. 
#list.setAdapter(postAdapter) : put into childAdded listener. 

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

    //retrieve post data from firebase 
    posts = new ArrayList<>(); 

    //ListView and PostAdapter 
    list = (ListView) findViewById(R.id.list); 
    postAdapter = new PostAdapter(this, posts); 

    DatabaseReference p = database.getReference("posts"); 
    p.addChildEventListener(new ChildEventListener() { 
     @Override 
     public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
      //get reference to post 
      HashMap<Object, Object> entry = (HashMap<Object, Object>) dataSnapshot.getValue(); 

      //convert to Post.class datatype 
      Post post = new Post(); 
      if (entry.get("category") != null) { post.setCategory(entry.get("category").toString()); } 
      if (entry.get("title") != null) { post.setTitle(entry.get("title").toString()); } 
      if (entry.get("description") != null) { post.setDescription(entry.get("description").toString()); } 
      if (entry.get("hasImg") != null) { post.setImg((boolean)entry.get("hasImg")); } 
      if (entry.get("postKey") != null) { post.setPostKey(entry.get("postKey").toString()); } 
      if (entry.get("posterID") != null) { post.setPosterID(entry.get("posterID").toString()); } 
      if (entry.get("schoolID") != null) { post.setSchoolID(entry.get("schoolID").toString()); } 
      if (entry.get("flagged") != null) { post.setFlagged((long)entry.get("flagged")); } 
      if (entry.get("time") != null) { post.setTime((long)entry.get("time")); }; 

      //add to ArrayList 
      posts.add(post); 
      postAdapter.add(post); 

      //attaching Adapter to ListView 
      list.setAdapter(postAdapter); 
      Log.d("LIST", "Item count: " + postAdapter.getCount()); 

      postAdapter.notifyDataSetChanged(); 
      Log.d("LIST", "Post Added: Posts: " + postAdapter.getCount()); 

     } 

     @Override 
     public void onChildChanged(DataSnapshot dataSnapshot, String s) { 

     } 

     @Override 
     public void onChildRemoved(DataSnapshot dataSnapshot) { 

     } 

     @Override 
     public void onChildMoved(DataSnapshot dataSnapshot, String s) { 

     } 

     @Override 
     public void onCancelled(DatabaseError databaseError) { 

     } 
    }); 

    } 
} 

Answer 2

因此，原来，这个问题曾与做我正在使用的ContraintLayout。显示格式和列表的一些调整。我已经更新了代码以反映我现在的工作实施。有趣的是，我的Log.d（...）调用里面getView（）仍然没有显示出来，即使对于所有的工作getView 必须被调用。仍然不知道如何解释一个。