Android Studio Not Applying My Design Changes - android-studio

Question

I'm trying to change the theme of some activities by removing the action bar or changing the title of it. At first i was doing it using the AppTheme option in the design tab. However, after searching online i knew that i was doing it the wrong way, so i proceeded to the AndroidManifest file to do my changes manually. Unfortunately, it's not working either. Here's the code of my manifest file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="net.wonderheart">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity"
android:label="Sign Up"/>
<activity
android:name=".Login"
android:label="Log In"/>
<activity android:name=".drawable.welcome">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".UserProfile"
android:theme="#style/AppTheme.NoActionBar"/>
<activity android:name=".HomePage" >
</activity>
</application>
</manifest>
Here are some of my activities that I'm trying to change:
Action Bar Title Changed Successfully
Action Bar Title Didn't Change
I'm using Android Studio 3.0 Preview and Kotlin. I hope you can help because i can't progress on my work without fixing this design issue!

Answer 1

You can fix problem two way.
1. Use common one theme for all activities and use code for hiding and showing action bar in onCreate method
// Set up the toolbar
val toolbar = findViewById(R.id.toolbar) as Toolbar
setSupportActionBar(toolbar)
var actionBar = supportActionBar
//For hiding android actionbar
actionBar.hide();
//For showing android actionbar
//actionBar.show();
Use custom style for activity where you don’t want to show action bar in example below I did it for application level but you can use it your way with your any other activities
style.xml
<resources>
<style name = "AppTheme" parent = "android:Theme.Holo.Light.DarkActionBar">
<!-- Customize your theme here. -->
</style>
<style name = "NoActionBar" parent = "#android:style/Theme.Holo.Light">
<item name = "android:windowActionBar">false</item>
<item name = "android:windowNoTitle">true</item>
</style>
</resources>
AndroidManifest.xml
<application
android:allowBackup = "true"
android:icon = "#drawable/ic_launcher"
android:label = "#string/app_name"
android:theme = "#style/NoActionBar" <!--This is the important line-->
>
<activity