我正在做一个比特币跟踪器应用程序，所以我可以学习json解析的基础知识，但我的应用程序层在运行应用程序时保持空白。这是我的 RecycleViewAdapter：
package Adapters;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.view.menu.MenuView;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.bumptech.glide.Glide;
import com.bumptech.glide.request.RequestOptions;
import com.example.angel.simplecrypto.R;
import java.util.List;
import Models.Currencies;
public class RecyclerViewAdapter extends RecyclerView.Adapter <RecyclerViewAdapter.MyViewHolder> {
private Context mContext;
private List<Currencies> mData;
RequestOptions option;
public RecyclerViewAdapter(Context mContext, List<Currencies> mData) {
this.mContext = mContext;
this.mData = mData;
option = new RequestOptions().centerCrop().placeholder(R.drawable.loading_shape).error(R.drawable.loading_shape);
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view;
LayoutInflater inflater=LayoutInflater.from(mContext);
view = inflater.inflate(R.layout.currency_row_item, parent,false);
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
holder.currency_price.setText(mData.get(position).getEur());
holder.currency_price2.setText(mData.get(position).getUsd());
}
@Override
public int getItemCount() {
return mData.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder{
TextView currency_price2;
TextView currency_price;
public MyViewHolder(View itemView) {
super(itemView);
currency_price2 = itemView.findViewById(R.id.price2);
currency_price= itemView.findViewById(R.id.price);
}
}
}
这是我的MainActivity：
package Activities;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;
import com.example.angel.simplecrypto.R;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
import Adapters.RecyclerViewAdapter;
import Models.Currencies;
public class MainActivity extends AppCompatActivity {
private final String JSON_URL = "https://min-api.cryptocompare.com/data/price?fsym=BTC&tsyms=EUR,USD";
private JsonArrayRequest request;
private RequestQueue requestQueue;
private List<Currencies> lstCurrencies;
private RecyclerView recyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lstCurrencies = new ArrayList<>();
recyclerView = findViewById(R.id.recyclerviewid);
jsonrequest();
}
private void jsonrequest() {
request = new JsonArrayRequest(JSON_URL, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
JSONObject jsonObject = null;
for (int i = 0; i < response.length(); i++){
try{
jsonObject=response.getJSONObject(i);
Currencies currencies = new Currencies();
currencies.setEur(jsonObject.getString("EUR"));
currencies.setUsd(jsonObject.getString("USD"));
} catch (JSONException e) {
e.printStackTrace();
}
}
setuprecyclerview(lstCurrencies);
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
}
private void setuprecyclerview(List<Currencies> lstCurrencies) {
RecyclerViewAdapter myadapter = new RecyclerViewAdapter(this, lstCurrencies);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(myadapter);
}
}
我只是想用2个项目测试回收查看器，但我不知道为什么没有出现。在我的 activity_main.xml 中，我创建了recyclerviewer，并且我有一个单独的.xml 来设计该recycleviewer中的项目。有任何想法吗？顺便说一下，我得到了这个错误：04-21 18：20：11.707 26586-26586 / com.example.angel.simplecrypto E / RecyclerView：没有连接适配器;跳过布局
答案 0 :(得分：1)
我想你忘记了lstCurrencies.add(currencies);
答案 1 :(得分：0)
您需要在jsonrequest()方法
lstCurrencies.add(currencies);
并定义您的RecyclerViewAdapter适配器类全局，并在listview中添加数据后添加myadapter.notifyDataSetChanged();
尝试这样......
public class MainActivity extends AppCompatActivity {
private final String JSON_URL = "https://min-api.cryptocompare.com/data/price?fsym=BTC&tsyms=EUR,USD";
private JsonArrayRequest request;
private RequestQueue requestQueue;
private List<Currencies> lstCurrencies;
private RecyclerView recyclerView;
RecyclerViewAdapter myadapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lstCurrencies = new ArrayList<>();
recyclerView = findViewById(R.id.recyclerviewid);
myadapter = new RecyclerViewAdapter(this, lstCurrencies);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(myadapter);
jsonrequest();
}
private void jsonrequest() {
request = new JsonArrayRequest(JSON_URL, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
JSONObject jsonObject = null;
for (int i = 0; i < response.length(); i++){
try{
jsonObject=response.getJSONObject(i);
Currencies currencies = new Currencies();
currencies.setEur(jsonObject.getString("EUR"));
currencies.setUsd(jsonObject.getString("USD"));
lstCurrencies.add(currencies);
} catch (JSONException e) {
e.printStackTrace();
}
}
adapter.notifyDataSetChanged();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
RequestQueue queue = Volley.newRequestQueue(this);
queue.add(request);
}
}
答案 2 :(得分：0)
您的json解析不正确，因此数据不会显示在recyclerview.Your API中返回json对象，您将解析array.Check您的API响应并检查您的json解析编码。