VolleyErrorHelper.java

package com.android.volley.error;

import java.util.HashMap;
import java.util.Map;

import android.content.Context;

import com.android.volley.NetworkResponse;
import com.android.volley.R;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class VolleyErrorHelper {

	private VolleyErrorHelper() {}

	/**
	 * 
	 * @param error
	 * @param context
	 * @return Returns appropriate message which is to be displayed to the user against
     * the specified error object.
	 */
	public static String getMessage(Object error, Context context) {
		if (error instanceof TimeoutError) {
			return context.getResources().getString(R.string.generic_server_down);
		} else if (isServerProblem(error)) {
			return handleServerError(error, context);
		} else if (isNetworkProblem(error)) {
			return context.getResources().getString(R.string.no_internet);
		}
		return context.getResources().getString(R.string.generic_error);
	}

    /**
     *
     * @param error
     * @param context
     * @return Return generic message for errors
     */
    public static String getErrorType(Object error, Context context) {
        if (error instanceof TimeoutError) {
            return context.getResources().getString(R.string.generic_server_timeout);
        } else if (error instanceof ServerError) {
            return context.getResources().getString(R.string.generic_server_down);
        } else if (error instanceof AuthFailureError) {
            return context.getResources().getString(R.string.auth_failed);
        } else if (error instanceof NetworkError) {
            return context.getResources().getString(R.string.no_internet);
        } else if (error instanceof NoConnectionError) {
            return context.getResources().getString(R.string.no_network_connection);
        } else if (error instanceof ParseError) {
            return context.getResources().getString(R.string.parsing_failed);
        }
        return context.getResources().getString(R.string.generic_error);
    }

	/**
	 * Determines whether the error is related to network
	 * 
	 * @param error
	 * @return
	 */
	private static boolean isNetworkProblem(Object error) {
		return (error instanceof NetworkError) || (error instanceof NoConnectionError);
	}

	/**
	 * Determines whether the error is related to server
	 * 
	 * @param error
	 * @return
	 */
	private static boolean isServerProblem(Object error) {
		return (error instanceof ServerError) || (error instanceof AuthFailureError);
	}

	/**
	 * Handles the server error, tries to determine whether to show a stock
	 * message or to show a message retrieved from the server.
	 * 
	 * @param err
	 * @param context
	 * @return
	 */
	private static String handleServerError(Object err, Context context) {
		VolleyError error = (VolleyError) err;

		NetworkResponse response = error.networkResponse;

		if (response != null) {
			switch (response.statusCode) {
			case 404:
			case 422:
			case 401:
				try {
					// server might return error like this { "error":
					// "Some error occured" }
					// Use "Gson" to parse the result
					HashMap<String, String> result = new Gson().fromJson(new String(response.data),
							new TypeToken<Map<String, String>>() { }.getType());

					if (result != null && result.containsKey("error")) {
						return result.get("error");
					}

				} catch (Exception e) {
					e.printStackTrace();
				}
				// invalid request
				return error.getMessage();

			default:
				return context.getResources().getString(R.string.generic_server_down);
			}
		}
		return context.getResources().getString(R.string.generic_error);
	}
}