title: picasso does not load image on start of appication
body: <p>I have used picasso on my MainActivity. On start of application it does not load image from the firebase link. However, when i go to another activity and go back, it starts loading image and show it. Actually, i am trying to get user image according to user ID (uid) in post.</p>
  
  <p>My MainActivity code:
  P.S. Sorry for such ugly coding, I am very beginner.</p>
  
  <pre><code>String userImage = null;
  String postKey = null;
  String uid = null;
  
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      mDatabase = FirebaseDatabase.getInstance().getReference().child("Posts");
      mDatabaseUsers = FirebaseDatabase.getInstance().getReference("Users");
      mUsers = FirebaseDatabase.getInstance().getReference("Users");
      mDatabaseUsers.keepSynced(true);
      mAuth = FirebaseAuth.getInstance();
      mPostList = findViewById(R.id.postList);
  
      mPostList.setHasFixedSize(true);
      mPostList.setLayoutManager(new LinearLayoutManager(this));
  }
  
  @Override
  protected void onStart() {
      super.onStart();
  
      mAuth.addAuthStateListener(mAuthListener);
  
      final FirebaseRecyclerAdapter&lt;Post, PostViewHolder&gt; firebaseRecyclerAdapter = new FirebaseRecyclerAdapter&lt;Post, PostViewHolder&gt;(
              Post.class,
              R.layout.post_row,
              PostViewHolder.class,
              mDatabase) {
  
          @Override
          protected void populateViewHolder(PostViewHolder viewHolder, Post model, int position) {
  
              postKey = getRef(position).getKey();
  
              viewHolder.setImage(getUserImage());
              viewHolder.setFrom(model.getFrom());
              viewHolder.setTo(model.getTo());
              viewHolder.setPrice(model.getPrice());
              viewHolder.setDate(model.getDate());
              viewHolder.setDate(model.getDate());
              viewHolder.setCar(model.getCar());
  
              viewHolder.mView.setOnClickListener(new View.OnClickListener() {
                  @Override
                  public void onClick(View view) {
  
                      Intent particularPostIntent = new Intent(MainActivity.this, ParticularPostActivity.class);
                      particularPostIntent.putExtra("PostId", postKey);
                      startActivity(particularPostIntent);
                  }
              });
          }
      };
  
      mPostList.setAdapter(firebaseRecyclerAdapter);
  }
  
  public static class PostViewHolder extends RecyclerView.ViewHolder {
  
      View mView;
  
      public PostViewHolder(View itemView) {
          super(itemView);
  
          mView = itemView;
      }
  
      public void setFrom(String from){
  
          TextView postFrom = mView.findViewById(R.id.rowFrom);
          postFrom.setText("From: " +from);
      }
  
      public void setTo(String to){
  
          TextView postTo = mView.findViewById(R.id.rowTo);
          postTo.setText("To: " + to);
      }
  
      public void setPrice(String price){
  
          TextView postPrice = mView.findViewById(R.id.rowPrice);
          postPrice.setText("Price: " + price);
      }
  
      public void setDate(String date){
  
          TextView postDate = mView.findViewById(R.id.rowDate);
          postDate.setText("Date: " + date);
      }
  
      public void setCar(String car){
  
          TextView postCar = mView.findViewById(R.id.rowCar);
          postCar.setText("Car: " + car);
      }
  
      public void setImage(String image){
  
          ImageView userImageView = mView.findViewById(R.id.rowProfileImage);
  
          Picasso.with(mView.getContext()).setLoggingEnabled(true);
          Picasso.with(mView.getContext()).load(image).placeholder(R.mipmap.ic_account_circle_black_48dp).into(userImageView);
      }
  }
  
  public String getUserImage(){
      mDatabase.child(postKey).addValueEventListener(new ValueEventListener() {
          @Override
          public void onDataChange(DataSnapshot dataSnapshot) {
  
              uid = (String) dataSnapshot.child("userID").getValue();
          }
  
          @Override
          public void onCancelled(DatabaseError databaseError) {
  
          }
      });
  
      mUsers.addValueEventListener(new ValueEventListener() {
          @Override
          public void onDataChange(DataSnapshot dataSnapshot) {
              userImage = (String) dataSnapshot.child(uid).child("Image").getValue();
          }
  
          @Override
          public void onCancelled(DatabaseError databaseError) {
  
          }
      });
  
      return userImage;
  }
  </code></pre>