Back4App - Example of Android App for Push Notifications using GCM (Push Activity)

pushNotification.java

package com.example.back4app.APP_NAME;

import android.app.Application;
import android.content.Context;

import com.parse.Parse;
import com.parse.ParseInstallation;

public class PushNotification extends Application {
    private static PushNotification instance = new PushNotification();
    public static final String APPLICATION_ID = "YOUR_APPLICATION_ID";
    public static final String CLIENT_KEY = "YOUR_CLIENT_KEY";
    public static final String BACK4APP_API = "https://parseapi.back4app.com/";

    public PushNotification() {
        instance = this;
    }

    public static Context getContext() {
        return instance;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Parse.initialize(new Parse.Configuration.Builder(this)
                .applicationId(APPLICATION_ID)
                .clientKey(CLIENT_KEY)
                .server(BACK4APP_API).build());
        ParseInstallation installation = ParseInstallation.getCurrentInstallation();
        installation.put("GCMSenderId", "YOUR_GCM_SENDER_ID");
        installation.saveInBackground();
        Parse.setLogLevel(Parse.LOG_LEVEL_VERBOSE);
    }
}