将数据从 Activity 传递到适配器，但是当我尝试将数据用作字符串时，它显示为 null

Question

我已将数据从我的活动传递到我的适配器。 调试时，我可以看到正确的数据已成功传递给我的适配器，但是当我尝试将其用作字符串时（例如，如果我想将文本设置为我刚刚传递的数据），它显示为 null .

• 在写着“this.uniquesharedIds = uniquesharedId;”的行上 - “uniqiuesharedIds”显示为 null。
• “uniquesharedId”表示有成功传递的数据。
• 我需要能够使用“uniqiuesharedIds”字符串。

对不起，如果这是一个愚蠢的问题。 将数据从活动发送到适配器总是让我感到困惑，我无法找到关于该主题的大量文档/视频。 谢谢你。

我在 On Create 方法中的活动

myadapter = new Invite_Contributors_Adapter(contributorInviteList, getIntent().getStringExtra("uniquesharedId"));

适配器

public class Invite_Contributors_Adapter extends RecyclerView.Adapter<Invite_Contributors_Adapter.myviewholder> {
    private ArrayList<Model_Invite_Contributors_List> model_invite_contributors_lists = new ArrayList<>();
    FirebaseAuth mAuth;
    private FirebaseUser currentuser;
    private DatabaseReference UsersReference;
    Context context;
    String uniquesharedIds;
    private InviteContributorsInterface inviteContributorsInterface;

    public Invite_Contributors_Adapter() {
    }

    public void updateInviteList (ArrayList list) {
        model_invite_contributors_lists .clear();
        model_invite_contributors_lists .addAll(list);
        notifyDataSetChanged();
    }

    public Invite_Contributors_Adapter(ArrayList<Model_Invite_Contributors_List>model_invite_contributors_lists, String uniquesharedId) {
        this.model_invite_contributors_lists = model_invite_contributors_lists;
        this.uniquesharedIds = uniquesharedId;
    }

    @NonNull
    @Override
    public Invite_Contributors_Adapter.myviewholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_layout_invite_contributors_list, parent, false);
        return new myviewholder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull myviewholder holder, int position) {
        holder.setData(model_invite_contributors_lists.get(position));
        mAuth = FirebaseAuth.getInstance();
        holder.Name.setText(uniquesharedIds);
    }


    @Override
    public int getItemCount() {
        return model_invite_contributors_lists.size();
    }


    static class myviewholder extends RecyclerView.ViewHolder implements DialogInterface.OnClickListener {
        TextView Name;
        CircleImageView profileImageView;

        public myviewholder(@NonNull View itemView) {
            super(itemView);
            Name = itemView.findViewById(R.id.contributor_name);
            profileImageView = itemView.findViewById(R.id.member_profile_picture);
        }

        @Override
        public void onClick(DialogInterface dialog, int which) {
        }

        public void setData(Model_Invite_Contributors_List model) {
            FirebaseUser currentuser;
            currentuser = FirebaseAuth.getInstance().getCurrentUser();
            DatabaseReference NameRef = FirebaseDatabase.getInstance().getReference(Strings.UsersReference);
            NameRef.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                    if (dataSnapshot.exists()) {
                        //this is very important. this says to not show the current user in the list of people to invite as a contributor.//
                        if (currentuser.getUid().equals(model.getUser_Id())){
                            ViewGroup.LayoutParams params = itemView.getLayoutParams();
                            params.height = 0;
                            itemView.setLayoutParams(params);
                        } else {
                            for(DataSnapshot ds : dataSnapshot.getChildren())
                            {
                                itemView.setVisibility(View.VISIBLE);
                                String profileImageString;
                                profileImageString = model.getProfileimage();
                                Glide.with(profileImageView.getContext()) //pulling in image and telling the image which imageview to go to once it comes in from the database
                                        .load(profileImageString)
                                        .placeholder(R.drawable.circle_placeholder)
                                        .error(R.drawable.circle_placeholder)
                                        .into(profileImageView);
                            }
                        }
                    }
                }

                @Override
                public void onCancelled(@NonNull DatabaseError databaseError) {
                }

            });
        }
    }



    public void setInterface (Invite_Contributors_Adapter.InviteContributorsInterface inviteContributorsInterface) {
        this.inviteContributorsInterface = inviteContributorsInterface;
    }

    public interface InviteContributorsInterface{

    }



}

Answer 1

您是否正在使用这样的适配器的任何主要构造函数？

myadapter = new Invite_Contributors_Adapter();

如果是，那么这就是问题所在。 如果您使用两个不同的构造函数初始化 object，那么您将获得稍后初始化的 object 的值。

确保检查适配器 object 然后继续。