我正在关注的这个问题
http://www.androidhive.info/2014/08/android-building-free-wallpapers-app-part-2/
到了我添加启动画面并开始“Volley Request”的地步。
本教程说的制作JSONObjectRequest时使用的代码是
JsonObjectRequest jsonObjReq = new JsonObjectRequest(Method.GET, url, null, new Response.Listener<JSONObject>()
但是当我输入时,它要求我导入Volley库,然后将其更改为
JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>()
这样做会导致错误无法解决构造函数。
我在SplashActivity.java中拥有的代码是:
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Window;
import android.widget.Toast;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
public class SplashActivity extends Activity {
private static final String TAG = SplashActivity.class.getSimpleName();
private static final String TAG_FEED = "feed", TAG_ENTRY = "entry",
TAG_GPHOTO_ID = "gphoto$id", TAG_T = "$t",
TAG_ALBUM_TITLE = "title";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
getActionBar().hide();
setContentView(R.layout.activity_splash);
// Picasa request to get list of albums
String url = AppConst.URL_PICASA_ALBUMS
.replace("_PICASA_USER_", AppController.getInstance()
.getPrefManager().getGoogleUserName());
Log.d(TAG, "Albums request url: " + url);
// Preparing volley's json object request
JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.GET, url,
null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Log.d(TAG, "Albums Response: " + response.toString());
List<Category> albums = new ArrayList<Category>();
try {
// Parsing the json response
JSONArray entry = response.getJSONObject(TAG_FEED)
.getJSONArray(TAG_ENTRY);
// loop through albums nodes and add them to album
// list
for (int i = 0; i < entry.length(); i++) {
JSONObject albumObj = (JSONObject) entry.get(i);
// album id
String albumId = albumObj.getJSONObject(
TAG_GPHOTO_ID).getString(TAG_T);
// album title
String albumTitle = albumObj.getJSONObject(
TAG_ALBUM_TITLE).getString(TAG_T);
Category album = new Category();
album.setId(albumId);
album.setTitle(albumTitle);
// add album to list
albums.add(album);
Log.d(TAG, "Album Id: " + albumId
+ ", Album Title: " + albumTitle);
}
// Store albums in shared pref
AppController.getInstance().getPrefManager()
.storeCategories(albums);
// String the main activity
Intent intent = new Intent(getApplicationContext(),
MainActivity.class);
startActivity(intent);
// closing spalsh activity
finish();
} catch (JSONException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),
getString(R.string.msg_unknown_error),
Toast.LENGTH_LONG).show();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Volley Error: " + error.getMessage());
// show error toast
Toast.makeText(getApplicationContext(),
getString(R.string.splash_error),
Toast.LENGTH_LONG).show();
// Unable to fetch albums
// check for existing Albums data in Shared Preferences
if (AppController.getInstance().getPrefManager()
.getCategories() != null && AppController.getInstance().getPrefManager()
.getCategories().size() > 0) {
// String the main activity
Intent intent = new Intent(getApplicationContext(),
MainActivity.class);
startActivity(intent);
// closing spalsh activity
finish();
} else {
// Albums data not present in the shared preferences
// Launch settings activity, so that user can modify
// the settings
Intent i = new Intent(SplashActivity.this,
SettingsActivity.class);
// clear all the activities
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
| Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(i);
}
}
});
// disable the cache for this request, so that it always fetches updated
// json
jsonObjReq.setShouldCache(false);
// Making the request
AppController.getInstance().addToRequestQueue(jsonObjReq);
}
}
我不确定该如何解决?
最佳答案
将您的空值转换为(String)null
例如:
JsonObjectRequest request = new JsonObjectRequest(JsonRequest.Method.POST, url, (String)null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response){
pDialog.hide();
Log.d("Reponse", response.toString());
Toast.makeText(getApplicationContext(), response.optString("name"), Toast.LENGTH_LONG).show();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError volleyError) {
volleyError.printStackTrace();
Log.d("Error = ", volleyError.toString());
pDialog.hide();
}
}){
@Override
protected Map<String, String> getParams(){
return params;
};
}
关于java - Volley -无法解析构造函数“JSONObjectRequest,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/31515885/