Question

请帮我这个，我创建了一个简单的recyclerview，但我没有在屏幕上输出，它是空白的这是我的适配器类，我一直试图调试这一整天没有成功，而且执行时没有错误

    public class ContactAdapter extends RecyclerView.Adapter<ContactAdapter.ViewHolder>
{
    private Activity context;
    private LayoutInflater mLayoutInflater;
    private List<Contact> contacts;
    public ContactAdapter(Activity context)
    {
        this.context=context;
        mLayoutInflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        contacts = new ArrayList<>();
    }
    @Override
    public ContactAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mLayoutInflater.inflate( R.layout.contact,parent,false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ContactAdapter.ViewHolder holder, int position) {
        Contact contact = contacts.get(position);
        holder.name.setText(contact.getName());
        holder.email.setText(contact.getEmail());
    }

    @Override
    public int getItemCount() {
        return contacts.size();
    }
    static class ViewHolder extends RecyclerView.ViewHolder
    {
        TextView name,email;
        ViewHolder(View itemView)
        {
            super(itemView);
            name= (TextView)itemView.findViewById(R.id.name);
            email=(TextView)itemView.findViewById(R.id.email);
        }
    }
    }

这是我的主要活动课

public class MainActivity extends AppCompatActivity {
RecyclerView recyclerView;
ContactAdapter adapter;
List<Contact> contacts = new ArrayList<>();

@Override
 protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView= (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter=new ContactAdapter(this);
Contact c1=new Contact("potato","xyz@gmail.com");

adapter.setHasStableIds(true);
recyclerView.setAdapter(adapter);
contacts.add(c1);
adapter.notifyDataSetChanged();
}
}

Answer 1

你是适配器

public class ContactAdapter extends RecyclerView.Adapter<ContactAdapter.ViewHolder>
{
    private Activity context;
    private LayoutInflater mLayoutInflater;
    private List<Contact> contacts;
    public ContactAdapter(Activity context,List<Contact> _list)
    {
        this.context=context;
        this.contacts=_list;
        mLayoutInflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        contacts = new ArrayList<>();
    }

    public void setDataChange(List<Contact> asList) {
        this.contacts = asList;
        //now, tell the adapter about the update
        notifyDataSetChanged();
    }

    @Override
    public ContactAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mLayoutInflater.inflate( R.layout.contact,parent,false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ContactAdapter.ViewHolder holder, int position) {
        Contact contact = contacts.get(position);
        holder.name.setText(contact.getName());
        holder.email.setText(contact.getEmail());
    }

    @Override
    public int getItemCount() {
        return contacts.size();
    }
    static class ViewHolder extends RecyclerView.ViewHolder
    {
        TextView name,email;
        ViewHolder(View itemView)
        {
            super(itemView);
            name= (TextView)itemView.findViewById(R.id.name);
            email=(TextView)itemView.findViewById(R.id.email);
        }
    }
    }

您的Activity

public class MainActivity extends AppCompatActivity 
{
 RecyclerView recyclerView;
 ContactAdapter adapter;
 List<Contact> contacts = new ArrayList<>();

 @Override
 protected void onCreate(Bundle savedInstanceState) 
 {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    recyclerView= (RecyclerView) findViewById(R.id.recyclerView);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));

    Contact c1=new Contact("potato","xyz@gmail.com");
    contacts.add(c1);
    adapter=new ContactAdapter(this,contacts);
    recyclerView.setAdapter(adapter);
}
}

Answer 2

在Adapter内，您必须创建该添加方法：

public void add(Contact c1) {
    chatModelList.add(c1);
    notifyItemInserted(contacts.size() - 1);
}

另一种方式：

List<Contact> result = getResult();
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
adapter = new ContactAdapter(this, result);
recyclerView.setAdapter(adapter);

private List<Contact> getResult() {
    List<Contact> contactList = new ArrayList<>();
    contactList.add(new Contact("A","B"));
    return contactList;
}

现在在适配器类中：

private Context context;
private List<Contact> contact = new ArrayList<>();


public ContactAdapter(Context context, List<Contact> contact) {
    this.context = context;
    this.contact = contact;
}

Answer 3

您的主管中有联系人列表，但您没有将这些联系人添加到适配器中。（在您的情况下，适配器列表始终为空）。

在适配器中创建一个方法，将联系人设置为适配器。

void setContacts(List<Contact> contacts) {
    this.contacts = contacts;
    notifiyDataSetChanged();
}

void addContacts(Contact  contact) {
    this.contacts.add(contact);
    notifyItemInserted(getItemCount()-1);
}

然后在主调用setContacts中，如果您想一次添加多个联系人，或使用addContacts一次添加一个联系人。

Recyclerview未填充，空白屏幕

3 个答案: