I am trying to learn how the POST method in Volley works but I keep getting the ClassCastException. I am trying Volley for the first time and have no idea what that means. I tried to google a little but havent figured it out yet. Any help is appreciated.
My code:
package com.example.piyu004.volleycommunication;
import android.app.Application;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.HashMap;
public class MainActivity extends Application {
/**
* Log or request TAG
*/
public static final String TAG = "VolleyPatterns";
/**
* Global request queue for Volley
*/
private RequestQueue mRequestQueue;
/**
* A singleton instance of the application class for easy access in other places
*/
private static MainActivity sInstance;
@Override
public void onCreate() {
super.onCreate();
tryPost();
// initialize the singleton
sInstance = this;
}
/**
* @return ApplicationController singleton instance
*/
public static synchronized MainActivity getInstance() {
return sInstance;
}
/**
* @return The Volley Request queue, the queue will be created if it is null
*/
public RequestQueue getRequestQueue() {
// lazy initialize the request queue, the queue instance will be
// created when it is accessed for the first time
if (mRequestQueue == null) {
mRequestQueue = Volley.newRequestQueue(getApplicationContext());
}
return mRequestQueue;
}
/**
* Adds the specified request to the global queue, if tag is specified
* then it is used else Default TAG is used.
*
* @param req
* @param tag
*/
public <T> void addToRequestQueue(Request<T> req, String tag) {
// set the default tag if tag is empty
req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
VolleyLog.d("Adding request to queue: %s", req.getUrl());
getRequestQueue().add(req);
}
/**
* Adds the specified request to the global queue using the Default TAG.
*
* @param req
* @param
*/
public <T> void addToRequestQueue(Request<T> req) {
// set the default tag if tag is empty
req.setTag(TAG);
getRequestQueue().add(req);
}
/**
* Cancels all pending requests by the specified TAG, it is important
* to specify a TAG so that the pending/ongoing requests can be cancelled.
*
* @param tag
*/
public void cancelPendingRequests(Object tag) {
if (mRequestQueue != null) {
mRequestQueue.cancelAll(tag);
}
}
public void tryPost() {
final String URL = "url address";
// Post params to be sent to the server
HashMap<String, String> params = new HashMap<String, String>();
params.put("id", "7");
params.put("address", "7");
JsonObjectRequest req = new JsonObjectRequest(URL, new JSONObject(params),
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
VolleyLog.v("Response:%n %s", response.toString(4));
Toast.makeText(getApplicationContext(),"success",Toast.LENGTH_LONG).show();
} catch (JSONException e) {
Toast.makeText(getApplicationContext(),"error",Toast.LENGTH_LONG).show();
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.e("Error: ", error.getMessage());
}
});
// add the request object to the queue to be executed
MainActivity.getInstance().addToRequestQueue(req);
}
}
I am also pasting my logcat:
05-08 17:02:15.173 20964-20964/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.piyu004.volleycommunication, PID: 20964
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.piyu004.volleycommunication/com.example.piyu004.volley communication.MainActivity}: java.lang.ClassCastException: com.example.piyu004.volleycommunication.MainActivity cannot be cast to android.app.Activity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2163)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2286)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:212)
at android.app.ActivityThread.main(ActivityThread.java:5135)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:878)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: com.example.piyu004.volleycommunication.MainActivity cannot be cast to android.app.Activity
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2154)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2286) at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:212)
at android.app.ActivityThread.main(ActivityThread.java:5135)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:878)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
at dalvik.system.NativeStart.main(Native Method)
Please let me know if you need any more information to help me
