我做了一个简单的项目，旨在获取附近餐馆的数据，并用它填充RecyclerView。但是，当我使用我的代码运行应用程序时，没有任何显示。 logcat没有显示任何错误，应用程序也没有崩溃。下面显示的是代码和logcat。非常感谢你的帮助。非常感谢你。 （顺便说一句，我从这个问题的示例代码中省略了api键。）
MainActivity.java
package com.example.matts.placessample;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
public class MainActivity extends AppCompatActivity {
public static ArrayList<HashMap<String, String>> placeList = new ArrayList<>();
public static HashMap<String, String> place = new HashMap<>();
private PlacesAdapter mAdapter;
private RecyclerView mRecyclerView;
private LinearLayoutManager mLayoutManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = findViewById(R.id.recyclerView);
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new PlacesAdapter(this, placeList);
mRecyclerView.setAdapter(mAdapter);
new GetPlaces().execute();
}
private class GetPlaces extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute () {
super.onPreExecute();
}
@Override
protected Void doInBackground (Void... arg0) {
HttpHandler sh = new HttpHandler();
String url = "https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=14.5649806,120.9934743&radius=500&type=restaurant&key=INSERT_API_KEY";
String jsonString = sh.makeServiceCall(url);
String TAG = "Hello";
if (jsonString != null) {
try {
JSONObject jsonObject = new JSONObject(jsonString);
JSONArray places = jsonObject.getJSONArray("results");
for (int i = 0; i < places.length(); i++) {
JSONObject p = places.getJSONObject(i);
String name = p.getString("name");
String vicinity = p.getString("vicinity");
place.put("name", name);
place.put("vicinity", vicinity);
placeList.add(place);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG).show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat for possible errors!",
Toast.LENGTH_LONG).show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
}
}
}
Adapter.java
package com.example.matts.placessample;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.HashMap;
import static com.example.matts.placessample.MainActivity.place;
import static com.example.matts.placessample.MainActivity.placeList;
class PlacesAdapter extends RecyclerView.Adapter<PlacesAdapter.PlaceViewHolder>{
private static ArrayList<HashMap<String, String>> mPlaceList;
private Context mContext;
private LayoutInflater inflater;
PlacesAdapter(Context context, ArrayList<HashMap<String, String>> list) {
mContext = context;
inflater= LayoutInflater.from(context);
mPlaceList = list;
}
static class PlaceViewHolder extends RecyclerView.ViewHolder {
private TextView name;
private TextView vicinity;
PlaceViewHolder(View itemView) {
super(itemView);
name = itemView.findViewById(R.id.name);
vicinity = itemView.findViewById(R.id.vicinity);
}
}
@Override
public PlaceViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemsView = LayoutInflater
.from(parent.getContext())
.inflate(R.layout.list_item, parent, false);
return new PlaceViewHolder(itemsView);
}
@Override
public void onBindViewHolder(PlaceViewHolder holder, int position) {
holder.name.setText(place.get("name"));
holder.vicinity.setText(place.get("vicinity"));
}
@Override
public int getItemCount() {
return placeList.size();
}
}
logcat的
10-14 15:04:55.276 21207-21207/? I/art: Late-enabling -Xcheck:jni
10-14 15:04:55.292 21207-21214/? E/art: Failed sending reply to debugger: Broken pipe
10-14 15:04:55.292 21207-21214/? I/art: Debugger is no longer active
10-14 15:04:55.292 21207-21214/? I/art: Starting a blocking GC Instrumentation
10-14 15:04:55.438 21207-21207/? W/System: ClassLoader referenced unknown path: /data/app/com.example.matts.placessample-2/lib/arm64
10-14 15:04:55.449 21207-21207/? I/InstantRun: starting instant run server: is main process
10-14 15:04:55.452 21207-21207/? V/Monotype: SetAppTypeFace- try to flip, app = com.example.matts.placessample
10-14 15:04:55.454 21207-21207/? V/Monotype: Typeface getFontPathFlipFont - systemFont = default#default
10-14 15:04:55.518 21207-21207/? W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
10-14 15:04:55.526 21207-21207/? V/Monotype: SetAppTypeFace- try to flip, app = com.example.matts.placessample
10-14 15:04:55.527 21207-21207/? V/Monotype: Typeface getFontPathFlipFont - systemFont = default#default
10-14 15:04:55.555 21207-21207/? V/BoostFramework: mAcquireFunc method = public int com.qualcomm.qti.Performance.perfLockAcquire(int,int[])
10-14 15:04:55.555 21207-21207/? V/BoostFramework: mReleaseFunc method = public int com.qualcomm.qti.Performance.perfLockRelease()
10-14 15:04:55.555 21207-21207/? V/BoostFramework: mAcquireTouchFunc method = public int com.qualcomm.qti.Performance.perfLockAcquireTouch(android.view.MotionEvent,android.util.DisplayMetrics,int,int[])
10-14 15:04:55.555 21207-21207/? V/BoostFramework: mIOPStart method = public int com.qualcomm.qti.Performance.perfIOPrefetchStart(int,java.lang.String)
10-14 15:04:55.555 21207-21207/? V/BoostFramework: mIOPStop method = public int com.qualcomm.qti.Performance.perfIOPrefetchStop()
10-14 15:04:55.557 21207-21207/? V/BoostFramework: BoostFramework() : mPerf = com.qualcomm.qti.Performance@f9a388e
10-14 15:04:55.557 21207-21207/? V/BoostFramework: BoostFramework() : mPerf = com.qualcomm.qti.Performance@db988af
10-14 15:04:55.657 21207-21207/? V/BoostFramework: BoostFramework() : mPerf = com.qualcomm.qti.Performance@2bdea7
10-14 15:04:55.657 21207-21207/? V/BoostFramework: BoostFramework() : mPerf = com.qualcomm.qti.Performance@caedf54
10-14 15:04:55.684 21207-21223/? D/NetworkSecurityConfig: No Network Security Config specified, using platform default
10-14 15:04:55.749 21207-21225/? I/Adreno: QUALCOMM build : dfab96b, I762e720a6a
Build Date : 01/31/17
OpenGL ES Shader Compiler Version: XE031.09.00.04
Local Branch :
Remote Branch :
Remote Branch :
Reconstruct Branch :
10-14 15:04:55.754 21207-21225/? I/OpenGLRenderer: Initialized EGL, version 1.4
10-14 15:04:55.754 21207-21225/? D/OpenGLRenderer: Swap behavior 1
10-14 15:04:55.786 21207-21207/? W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
10-14 15:04:56.865 21207-21207/com.example.matts.placessample V/BoostFramework: BoostFramework() : mPerf = com.qualcomm.qti.Performance@1b40a67
答案 0 :(得分：0)
获取新数据后需要通知您的适配器。
最简单的方法是将default提取到字段，然后在mAdapter调用onPostExecute
当然，只有当您从API获得正确答案时，它才会起作用。