not able to retrieve string from parse database with query

After getting some sleep then doing more research and tinkering I found the problem. The problem isn't in my code; it's in my network... well not entirely. You see my code runs ... at well run-time (As fast as my phone can process it); however, the method

query.findInBackground(new FindCallback<ParseObject>()

runs asynchronously meaning that it does not run at the speed of my other code. Which makes sense if you think about it because it has to send and wait for a response from a database. That's why when I made a toast inside it, the data was there in the string but when I tried to make a toast a few lines later, outside of the method, the data was not there. It was null.

Here's an example. I make a toast at the end of on create with this code

@Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // initialise and set toolbar as actionbar
        toolbar = (Toolbar) findViewById(R.id.tool_bar);
        setSupportActionBar(toolbar);

        // initialize nav bars
        initNavBars();

        // initialize drawer layout
        NavigationView navView = (NavigationView) findViewById(R.id.navigation_view);

        // initialize nav drawer
        navDrawer = (DrawerLayout) findViewById(R.id.drawer);
        initNavDrawer(navDrawer);

        // initialize layout manager for recycler view
        RecyclerView.LayoutManager mainLayoutManager = new LinearLayoutManager(this);

        // initialize data for all classes before setting adapter
        initClassData();  // <---- MY PARSE QUERY IS IN THIS METHOD

        // set the adapter for recycler view
        RecyclerView.Adapter mainAdapter = new MainRecyclerAdapter(classrooms);

        // initialize recycler view elements
        RecyclerView mainRecyclerView = (RecyclerView) findViewById(R.id.main_recycler_view);

        // add layout manager to recycler view
        mainRecyclerView.setLayoutManager(mainLayoutManager);

        // add adapter to recycler view
        mainRecyclerView.setAdapter(mainAdapter);

        Toast.makeText(getApplicationContext(), userClasses[PERIOD1], Toast.LENGTH_SHORT).show(); // <----- HERE IS MY TOAST
    }

When I run it, the toast is empty because the string is still null, but if I run it with this code

 @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // initialise and set toolbar as actionbar
        toolbar = (Toolbar) findViewById(R.id.tool_bar);
        setSupportActionBar(toolbar);

        // initialize nav bars
        initNavBars();

        // initialize drawer layout
        NavigationView navView = (NavigationView) findViewById(R.id.navigation_view);

        // initialize nav drawer
        navDrawer = (DrawerLayout) findViewById(R.id.drawer);
        initNavDrawer(navDrawer);

        // initialize layout manager for recycler view
        RecyclerView.LayoutManager mainLayoutManager = new LinearLayoutManager(this);

        // initialize data for all classes before setting adapter
        initClassData(); // <---- PARSE QUERY IS STILL IN THIS METHOD

        // set the adapter for recycler view
        RecyclerView.Adapter mainAdapter = new MainRecyclerAdapter(classrooms);

        // initialize recycler view elements
        RecyclerView mainRecyclerView = (RecyclerView) findViewById(R.id.main_recycler_view);

        // add layout manager to recycler view
        mainRecyclerView.setLayoutManager(mainLayoutManager);

        // add adapter to recycler view
        mainRecyclerView.setAdapter(mainAdapter);

        final Handler handler = new Handler();
        handler.postDelayed(new Runnable()
        {
            @Override
            public void run()
            {
                // Do something after 5s = 5000ms
                Toast.makeText(getApplicationContext(), userClasses[PERIOD1], Toast.LENGTH_SHORT).show();
            }
        }, 5000);
    }

In this example I forced the toast to wait five seconds to allow

query.getFirstInBackground(new GetCallback<ParseObject>()

to finish querying the database and when I run it, the toast displays the string correctly.

So if your program relies on a parse query to get important data, you have to structure your code in a way to allow for a second or two to pass to let the parse query return.

Or you could alternatively store the data locally and then you can use the database as a backup for the data and check to make sure it is the same every time the user wants to switch it or somethings.

Thank you Ajay and Rasika I would still be trying to figure why it was not working if it weren't you.