<activity
    android:name="first Activity Name"
    android:theme="@android:style/Theme.Translucent.NoTitleBar">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

In Android studio 2.0 or above version it is happening because of instant run. by removing it from settings>Bulid, Execution, Deployment> Instant run and disable all the check boxes over there here is snapshot for the settings screen.