使用自定义适配器时，空RecyclerView [英] Empty RecyclerView when using custom Adapter
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问题描述
我想填充我 RecyclerView 从云数据（ parse.com ）。然而，最终的结果是一个空的 RecyclerView 。虽然我能够检索从云中的数据，我看不到屏幕上的任何。
下面是主要的活动code：
公共类BigBoard扩展ActionBarActivity {私人列表＆LT;＆人GT;者;
私人RecyclerView RV;
RVAdapter适配器;
字符串A，B;@覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
Parse.initialize（这一点，APP-ID，客户端密钥）;
的setContentView（R.layout.activity_big_board）;
适配器=新RVAdapter（人）;
RV =（RecyclerView）findViewById（R.id.rv）; LinearLayoutManager LLM =新LinearLayoutManager（本）;
rv.setLayoutManager（LLM）;
rv.setHasFixedSize（真）; initializeData（）;
initializeAdapter（）;}私人无效initializeData（）{
人=新的ArrayList＆LT;＆GT;（）;
ParseQuery＆LT;＆的parseObject GT;查询=新ParseQuery＆LT;＆的parseObject GT;（资格证书）;
query.findInBackground（新FindCallback＆LT;＆的parseObject GT;（）{
公共无效完成（列表＆LT;＆的parseObject GT; credentialList，ParseException的E）{
如果（E == NULL）{
的for（int i = 0; I＆LT; credentialList.size（）;我++）
{
A = credentialList.get（I）.getString（姓名）;
B = credentialList.get（I）.getString（姓）;
persons.add（新的Person（A，B））; Log.d（OUT，所以瓦尔:: ------＆gt;中+ A + B）;
adapter.notifyDataSetChanged（）; }
}其他{
Log.d（得分，错误：+ e.getMessage（））;
}
}
}）;
//persons.add(new人（艾玛·威尔逊，23岁））;
//persons.add(new人（拉维Maiss，25岁））;
//persons.add(new人（利利瓦，35岁））;}私人无效initializeAdapter（）{ rv.setAdapter（适配器）;
}
和我能登录，我从云收到价值，另外，如果我使用一些pre定义的值code正常工作。正如你所看到的注释行：
//persons.add(new人（艾玛·威尔逊，23岁））;
//persons.add(new人（拉维Maiss，25岁））;
//persons.add(new人（利利瓦，35岁））;
和，这里是code到Adapter类：
公共类RVAdapter扩展RecyclerView.Adapter＆LT; RVAdapter.PersonViewHolder＆GT; {公共静态类PersonViewHolder扩展RecyclerView.ViewHolder { CardView简历;
TextView的PERSONNAME;
TextView的人士;
// ImageView的personPhoto; PersonViewHolder（查看ItemView控件）{
超（ItemView控件）;
CV =（CardView）itemView.findViewById（R.id.cv）;
PERSONNAME =（TextView中）itemView.findViewById（R.id.person_name）;
人物=（TextView中）itemView.findViewById（R.id.person_age）;
// personPhoto =（ImageView的）itemView.findViewById（R.id.person_photo）;
}
}清单＆LT;＆人GT;者;RVAdapter（列表＆LT;＆人GT;人）{
this.persons =者;
}@覆盖
公共无效onAttachedToRecyclerView（RecyclerView recyclerView）{
super.onAttachedToRecyclerView（recyclerView）;
}@覆盖
公共PersonViewHolder onCreateViewHolder（ViewGroup中ViewGroup中，int i）以{
视图V = LayoutInflater.from（viewGroup.getContext（））膨胀（R.layout.item，ViewGroup中，假的）。
PersonViewHolder PVH =新PersonViewHolder（V）;
返回PVH;
}@覆盖
公共无效onBindViewHolder（PersonViewHolder personViewHolder，int i）以{
personViewHolder.personName.setText（persons.get（I）。名称）;
personViewHolder.personAge.setText（persons.get㈠.surname）;
// personViewHolder.personPhoto.setImageResource（persons.get㈠.photoId）;
}@覆盖
公众诠释getItemCount（）
{
如果（人！= NULL）
{
返回persons.size（）;
}
其他
{
返回0;
}
}
}和Person类：
类Person
{
字符串名称;
串姓;
人（字符串名称，字符串河畔）
{
this.name =名称;
this.surname =河畔; }
}虽然我使用了
notifyDataSetChanged（）方法，为什么我不能得到任何结果，我应该考虑使用不同的线程或的AsyncTask （），寻找答案，谢谢！解决方案但问题是，你实际上并没有设置数据插入适配器。首先添加适配器的内部下面的方法：
公共无效setPersons（列表＆LT;＆人GT;人）{
this.persons =者;
notifyDataSetChanged（）;
}在您的调用类的initializeData（）方法，再经过就叫
adapter.setPersons（人）。您不必再次调用如下：`私人无效initializeAdapter（）{ rv.setAdapter（适配器）;
}`所以基本上只需要调用
adapter.setPersons（人）每当你从服务器获取新的数据。I am trying to populate my
RecyclerViewwith data from cloud(parse.com). However, The end result is an EmptyRecyclerView. Though I am able to retrieve the data from cloud, I don't see any on the Screen.Here is the main Activity Code:
public class BigBoard extends ActionBarActivity { private List<Person> persons; private RecyclerView rv; RVAdapter adapter; String a,b; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Parse.initialize(this, "app-id", "client-key"); setContentView(R.layout.activity_big_board); adapter = new RVAdapter(persons); rv=(RecyclerView)findViewById(R.id.rv); LinearLayoutManager llm = new LinearLayoutManager(this); rv.setLayoutManager(llm); rv.setHasFixedSize(true); initializeData(); initializeAdapter(); } private void initializeData(){ persons = new ArrayList<>(); ParseQuery<ParseObject> query = new ParseQuery<ParseObject>("Credentials"); query.findInBackground(new FindCallback<ParseObject>() { public void done(List<ParseObject> credentialList, ParseException e) { if (e == null) { for(int i=0;i<credentialList.size();i++) { a=credentialList.get(i).getString("Name"); b=credentialList.get(i).getString("SurName"); persons.add(new Person(a,b)); Log.d("OUT", "So the Val::------> " +a +b); adapter.notifyDataSetChanged(); } } else { Log.d("score", "Error: " + e.getMessage()); } } }); //persons.add(new Person("Emma Wilson", "23 years old")); //persons.add(new Person("Lavery Maiss", "25 years old")); //persons.add(new Person("Lillie Watts", "35 years old")); } private void initializeAdapter(){ rv.setAdapter(adapter); }And I am able to log the Values that I receive from Cloud, also, the code works fine if I using some pre-defined values. As you can see the commented lines:
//persons.add(new Person("Emma Wilson", "23 years old")); //persons.add(new Person("Lavery Maiss", "25 years old")); //persons.add(new Person("Lillie Watts", "35 years old"));
And, here is the code to the Adapter class:
public class RVAdapter extends RecyclerView.Adapter<RVAdapter.PersonViewHolder> { public static class PersonViewHolder extends RecyclerView.ViewHolder { CardView cv; TextView personName; TextView personAge; //ImageView personPhoto; PersonViewHolder(View itemView) { super(itemView); cv = (CardView)itemView.findViewById(R.id.cv); personName = (TextView)itemView.findViewById(R.id.person_name); personAge = (TextView)itemView.findViewById(R.id.person_age); //personPhoto = (ImageView)itemView.findViewById(R.id.person_photo); } } List<Person> persons; RVAdapter(List<Person> persons){ this.persons = persons; } @Override public void onAttachedToRecyclerView(RecyclerView recyclerView) { super.onAttachedToRecyclerView(recyclerView); } @Override public PersonViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) { View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item, viewGroup, false); PersonViewHolder pvh = new PersonViewHolder(v); return pvh; } @Override public void onBindViewHolder(PersonViewHolder personViewHolder, int i) { personViewHolder.personName.setText(persons.get(i).name); personViewHolder.personAge.setText(persons.get(i).surname); // personViewHolder.personPhoto.setImageResource(persons.get(i).photoId); } @Override public int getItemCount() { if(persons!=null) { return persons.size(); } else { return 0; } } }And the Person class :
class Person { String name; String surname; Person(String name, String sur) { this.name = name; this.surname = sur; } }Though I use an
notifyDataSetChanged()method, why am I not able to get any result, should I consider using a different thread orAsyncTask(), looking for Answers, Thanks !解决方案The problem is, you are not actually setting the data into the adapter. First off add the following method inside of your adapter :
public void setPersons(List<Person> persons){ this.persons = persons; notifyDataSetChanged(); }Then after the initializeData() method in your calling class just call
adapter.setPersons(persons). You don't have to call the following again:`private void initializeAdapter(){ rv.setAdapter(adapter); }`So basically just call
adapter.setPersons(persons)whenever you get new data from the server.这篇关于使用自定义适配器时，空RecyclerView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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