Question

I want to get Application context to use with glide in non-activity class. But it's always returning null. This is the code I'm using - how might I solve this?

I created Contextor for get application context to use in non-activity model.

public class Contextor {

    private static Contextor instance;

    public static Contextor getInstance() {
        if (instance == null)
            instance = new Contextor();
        return instance;
    }

    private Context mContext;

    private Contextor() {}

    public void init(Context context) {
        mContext = context;
    }

    public Context getContext() {
        return mContext;
    }
}

In myRecyclerViewAdapter.

public class RecyclerViewNewfeedAdapter extends RecyclerView.Adapter<RecyclerViewNewfeedAdapter.PostViewHolder> {

private List<Post> mPostList;
private Context mContext;

class PostViewHolder extends RecyclerView.ViewHolder {
    TextView username;
    TextView text;
    CircleImageView profileImage;

    PostViewHolder(View view) {
        super(view);
        username = (TextView) view.findViewById(R.id.tvPostUsername);
        text = (TextView) view.findViewById(R.id.tvPostText);
    }
}

public RecyclerViewNewfeedAdapter(List<Post> mPostList) {
    this.mPostList = mPostList;
}

@Override
public PostViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.post_row, parent, false);

    initInstances();

    return new PostViewHolder(itemView);
}

private void initInstances(){
    mContext = Contextor.getInstance().getContext();
}

@Override
public void onBindViewHolder(final PostViewHolder holder, int position) {
    final Post post = mPostList.get(position);

    FirebaseRef.mUserInfoRef.child(post.getOwnerPost()).addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            holder.username.setText(dataSnapshot.child("username").getValue(String.class));
            Glide.with(mContext).load(dataSnapshot.child("profileImage").getValue(String.class)).placeholder(R.drawable.ic_default_profile_image).diskCacheStrategy(DiskCacheStrategy.ALL).into(holder.profileImage);
            holder.text.setText(post.getTextPost());
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });
}
@Override
public int getItemCount() {
    return mPostList.size();
}

Answer 1

Why this context always returned null?

because you never call init(Context context) on Contextor.getInstance(). Btw, it seems a little of overkill to have this object when you can easily assign parent.getContext() to mContext

Answer 2

Its because your Contextor doesn't have any context, first give it a context then get from there.

I would suggest using adapter's contructor like this

Context ctx;

public RecyclerViewNewfeedAdapter(List<Post> mPostList, Context context) {
    this.mPostList = mPostList;
    this.ctx = context;
}

Why this context always returned null?

2 个答案: