java Volley - 无法解析构造函数“JSONObjectRequest”
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Volley - Cannot Resolve Constructor "JSONObjectRequest
提问by x10sion
I have this issue where I am following
我有这个问题，我正在关注
http://www.androidhive.info/2014/08/android-building-free-wallpapers-app-part-2/
http://www.androidhive.info/2014/08/android-building-free-wallpapers-app-part-2/
and have come to the point where I add a splash screen and am starting the Volley Request.
并且已经到了添加启动画面并开始 Volley Request 的地步。
The code the tutorial says to use when making the JSONObjectRequest is
教程说在制作 JSONObjectRequest 时使用的代码是
JsonObjectRequest jsonObjReq = new JsonObjectRequest(Method.GET, url, null, new Response.Listener<JSONObject>()
but when I type that out it asks me to import Volley library, which then changes it to
但是当我输入它时，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>()
Doing this brings up the error cannot resolve constructor.
这样做会导致错误无法解析构造函数。
The code I have in my SplashActivity.java is:
我在 SplashActivity.java 中的代码是：
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);
}
}
I'm not sure what to do in order to fix this?
我不知道该怎么做才能解决这个问题？
回答by Dharmbir Singh
Cast your null value like (String)null
将您的空值转换为(String)null
For eg:-
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;
};
}
回答by Karrthik
The error is due to the usage of higher volley version. please use
错误是由于使用了更高的截击版本。请用
compile 'com.mcxiaoke.volley:library:1.0.0'
in the gradle dependency. It worked out for me, when I got the same problem.
在 gradle 依赖项中。当我遇到同样的问题时，它对我有用。
回答by Gopal Singh Sirvi
The parameters in your constructor for request is not correct so you are facing the problem. The correct code to create a JsonObjectRequestis
请求的构造函数中的参数不正确，因此您遇到了问题。创建一个的正确代码JsonObjectRequest是
JsonObjectRequest request = new JsonObjectRequest(Method.GET, url, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject arg0) {
// TODO Auto-generated method stub
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError arg0) {
// TODO Auto-generated method stub
}
});
