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Fragment showing nothing when starting my app for first time

I have an app with bottom navigation fragment activity
I have placed text views and buttons on my home fragment.
further these fragments are placed in a frame layout.
when I launch my app my home fragment shows nothing just blank screen it loads everything when I
switch between fragments.
I want to fix this, so that when I launch my app everything that is on my home fragment shows up.

because you didn't specify the first fragment to show,
in the onCreate you have to do this :
first checked the bottomNavigation item, that you want to start with :
bottomNavigation.getMenu().findItem(R.id.item).setChecked(true);
then put the first fragment in frame layout

For supporting different screen size why should i use fragment in android instead of activity

I am beginner to android..I am started new android project..for supporting
different screen size..in fragment documentation they given to use fragment..but
why cant i use activity in android..if i use activity or fragment..which i should i use in this both..please dont give link of activity or fragment..please anyone answer me..i dont know which to use?...i want about all documentation they given about activity and fragment but i dint understand which to use..below is the link i read about fragment..if i use activity i should do more codings?
https://developer.android.com/guide/components/fragments.html

In fact you can't use a Fragment alone, Fragments are inside the Activity.
One point of using the Fragments for supporting different screen sizes is the ability to implement some views like a "Master/Detail" view.
A Fragment, as its name says, is a part of a bigger controller "the Activity", its reference can be removed and it's cleaner than having a big massive Activity to handle all the states of a view.
So the use case is completely depends on your project and its User Interface. I'd be glad to help you if you give me more information about your project and its design.

I think you will need at least one activity. And then for better handling different device rotations and screen sizes you can use one or more fragments inside this activity.
I try to explain this with an example:
You want to create a nice music player app which should look nice in portrait and landscape mode.
You split your app up into three fragments:
Here you can see how the app looks in portrait mode. The activity shows two fragments: The first fragment only consists of a listview. There the song titles are listed. On the bottom you can see the second fragment, which displays the song title of the current playing song and got a button for pausing the music.
When your user uses the music player app on a tablet in landscape mode you have more space for displaying stuff. Then the activity shows the list fragment (which also gets displayed in portrait mode) and it shows a third fragment which shows detailed information about the current playing song (e.g. the album image) and a progress bar.
By using fragments you only need to write the code for the list once.

Sweet and Simple thing, What i recommend is always use Fragments,
But for Fragment you will require Activity.
Take it in this way , Activity is a Canvas on which you can put any number of Fragments.
Whatever your UI is always use Fragment present on a activity if you want to show one screen even then also, So that you will always have Flexibilty to use all those cool things which fragments provides,maybe in future or in current.
If you use activity it has limits,FOR EXAMPLE, LIKE in INSTAGRAM AT BOTTOM, It has FIVE OPTIONS, Suppose THOSE OPTIONS ARE ON A ACTIVITY AND BY CLICKING ON THEM YOU CAN SWITCH TO DIFFERENT FRAGMENTS.
For more info:
Here is the most accepted answer for this topic.

Navigation drawer use at another activity only, not in main activity

I have a project containing different activities like: main activity, signup activity, login activity and track activity. Now I want to create another activity which will contain navigation drawer. And the point is "I don't want to use navigation drawer at any other activity".
All the example so far I found at searching # net provide example using main activity. But I don't want to use navigation bar at main activity.

If you are using Android Studio, follow these steps,
1. Right click on app.
2. new -> activity -> navigationDrawerActivity
this way only your new activity will have navigation drawer.

Android - add Swipe View/tabs to only SOME fragments

Currently, my app is using a navigation drawer for my fragments. However, I have 2 fragments that are related, I would like to put these under one heading on the navigation drawer and then have 2 tabs to switch between the related fragments once I select that choice on the drawer.
Is this possible with only one activity or would I have to implement another activity specifically for the tab? I've considered only adding the tabs once the right fragment is committed but that leaves the question of how to remove it once I switch to a fragment that doesn't require the tabs.
I'd also like to avoid having to implement another activity as I am trying to keep the navigation available through my whole app. I'd rather not have to create an identical drawer and then have to keep things consistent between the 2 drawers.
Edit:
So far, I've managed to make a parent fragment that has a viewpager, fragmentpageradapter, and tablayout. Swiping between the 2 tabs does indeed shift between my 2 desired child fragments. However, I am unable to change a textview in one of my child fragments from my MainActivity. I'm guessing the reason why this is the case is because technically, my parent fragment is in view, not my child fragment. Any suggestions to get around this?
Hierarchy:
MainActivity
-Navigation Drawer
--Fragment1
--Fragment2
--Fragment3
--Fragment4
---FragmentPagerAdapter (under Fragment4, tabs)
----SubFrag1
----SubFrag2

Here's how you might use FragmentStatePagerAdapter to swipe across a Fragment:
http://developer.android.com/intl/es/training/implementing-navigation/lateral.html
I hope it help you.

Batch edit activities in Android Studio

I have recently decided to add a Navigation Drawer to every screen in my app. I already have the working code. Is there a faster way to add the same layout to every screen or must I do this manually?

One way you could do it is to create an Activity or Fragment class say BaseActivity that all your Activity or Fragment will inherit, and put your Navigation Drawer logic there.