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Splash Screen Doesn't Display First On The Application

Good day, I'm doing a project and, I'm new with android development also, I just want to ask how to display my[the] splash screen first on my app (when starting up my application). Whenever I run it on emulator or on my device it directly go to my main activity.
Splash Screen Image
Main NavDrawer
I even reorder my manifest file list - and place the splash screen first
here my code
<!-- For Splash Screen -->
<activity
android:name=".activities.SplashScreen"
android:screenOrientation="portrait"
android:theme="#style/Theme.AppCompat.NoActionBar" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- For Main Activity -->
<activity android:name=".activities.MainActivity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Whenever I exit my app and start again, my splash screen is gone! It directly go to Main Activity.
Thanks in advance! :)

You are having 2 LAUCHERS...
Make sure that only the Splash Screen Activity is the LAUNCHER.
Let the Main Activity be a DEFAULT one (and also the HOME one).

How the android app's first activity launched?

when we created a helloworld application using ADT, The "MainActivity" will be loaded, Because every program has a entry, such as the "main" function, For android apps, We can declare many activities in the file called "AndroidManifest.xml", So I wanna know how this activity launched by android framework? which is android apps "main" entry ?

Manifest tells android which activity to launch. Actually, when you click app icon, OS consults with application's manifest file and looks for the launcher activity. You can declare any activity as your launcher by writing this inside your activity tag in manifest.
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
Manifest always acts as interface between your application and OS. It provides all the information about your app to OS like what are the permissions, what activities, what receivers you are using in your app including your LAUNCHER ACTIVITY.

Only one activity should have the "main" action and "launcher" category...
So in the AndroidManifest.xml file, you should essentially have only one:
action android:name="android.intent.action.MAIN"
category android:name="android.intent.category.DEFAULT"
Activities will very often need to support the CATEGORY_DEFAULT so that they can be found by Context.startActivity(). So, CATEGORY_DEFAULT can appear number of times.
Android does not grab whichever one appears first in the manifest but it starts with activity having CATEGORY_LAUNCHER.
CATEGORY_LAUNCHER : The activity can be the initial activity of a task and is listed in the top-level application launcher.

because of this
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />

the activity declared with intent filter
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
will be launched first.
<activity
android:name="com.example.hello.HelloActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

Every Activity of my application is shown as an app on its own

Just like the title says, for some reason which I dont understand, Every Activity I create in my application is shown as an icon for an application on the phone's app menu.
Could someone please help me solve this wierd problem?
If you need some code just ask for it (I dont know which code is related with these kind of stuff).
Thanks!

In your manifest remove these lines from all Activities except the one you want to open on:
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
Example:
<activity
android:name="your.package.name.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<!-- This line declares this Activity as the start point -->
<action android:name="android.intent.action.MAIN" />
<!-- This line adds a launcher icon -->
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="your.package.name.OtherActivity"
android:label="#string/app_name" >
</activity>

In your manifest file you must have set launcher intent-filter for all of your activities.. Keep launcher intent-filter only in launcher activity..

How to change the startup activity in android?

I have two activities namely login and calendar in my Application. Currently my startup activity is "calendar". I want to run the login as first activity not calendar.

The startup activity [Launcher Activity] is declared in the projects' AndroidManifest.xml file
Look for that activity tag in the manifest which looks like this
<activity android:name=".Main"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Look at the attribute android:name. Main is the class which is launched when the app starts. Currently your calendar activity name should be there. Change that to the .classpath of your activity that you want to launch.
That should do it. You may also want to do the hello world application in the tutorials and go through the docs a little to see how Android Applications work.

Add Intent filter to the Activity in which you want startup.
In your case Modify the AndroidManifest.xml file as follows
<activity android:name=".login"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

remove the intent-filter code from calendar Activity tag in manifest and add it to the Activity you wanna load first
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
I mean paste it in the activity you like to run as default.
<activity
android:name="com.example.gridviewimages.AnotherActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Where as
From the docs
category -- Gives additional information about the action to execute. For example,
CATEGORY_LAUNCHER means it should appear in the Launcher as a top-level application, while
CATEGORY_ALTERNATIVE means it should be included in a list of alternative actions the user can
perform on a piece of data.
MAIN means that this activity is the entry point of the application, i.e. when you launch the application, this activity is created.

You want the Application element of the Android Manifest file. You can see details here.
Look at the name attribute, this points to the Application class.

In android every .java file becomes an app on the phone!

I have 6 .java files under one package.In eclipse, after I export the .apk and install the app on the phone or if i run the app on the emulator, there are 6 applications created, one for each .java file! The java files are different screens in my app.So i can open any java file by clicking on the icon in the menu.I only want one of them to be openable through the icon in the menu. So basically, only one icon should be seen in the main menu, which upon clicking opens the first activity in the manifest file!
Any idea whats wrong?
Thanks.

My assumption:
You registered all your Activities in the AndroidManifest (which is right) but as intent-filter you always used
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
That intent-filter tells Android to add the Activity to the launcher. Remove those Intent-filters (except one Activity that's going to be your main entry point) and it should work.

What does your manifest say? It might specify that all activities are shown as seperate apps...

Just check your AndroidManifest.xml file and modify your activity same as below code example:
<activity android:name=".MainActivity"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".SecondActivity"
android:label="SecondActivity">
</activity>
So if you mark the above code then you can easily come to know that the below code mention that this activity is going to be act as a launcher activity.
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

Try to mention the intent-filter action as MAIN and Category as Launcher only for your entry activity in your app.
<intent-filter>
<action android:name="android.intent.action.MAIN"></action>
<category android:name="android.intent.category.LAUNCHER"></category>
</intent-filter>.
Remove this for all other activities except the entry point for your app.
Hope this helps.