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VNSGU BCA Sem 3: Mobile App Dev (305-2) Practical Solutions - April 2025 Set A

Paper Information

Attribute	Value
Subject	Mobile Application Development - I
Subject Code	305-2
Set	A
Semester	3
Month/Year	April 2025
Max Marks	25
Paper	View Paper | Download PDF

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Questions & Solutions

Q1: Fullscreen & Screen Orientation Toggle

Max Marks: 20

Create a Mobile Application in Android to hide title bar and open in Full Screen Size and change the orientation of the screen on button click.

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1. Concept Explanation

Hiding the Title Bar and Action Bar

In Android, the title bar (Action Bar) can be hidden in two ways:

1. XML Theme Config: Setting the theme in themes.xml to a NoActionBar variant (e.g. Theme.MaterialComponents.DayNight.NoActionBar).
2. Programmatic Call: Using supportActionBar?.hide() inside the Activity's onCreate() method.

Running in Fullscreen Mode

To display an Activity in true fullscreen (hiding the status bar, navigation bar, etc.):

• Modern APIs (API 30+): Use WindowInsetsController to hide system bars.
• Legacy APIs: Use window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN).

Toggling Screen Orientation Programmatically

You can change the screen orientation of an activity on-the-fly by setting the requestedOrientation property:

• ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
• ActivityInfo.SCREEN_ORIENTATION_PORTRAIT

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2. Algorithm & Step-by-Step Logic

1. Design User Interface (activity_main.xml): Add a single Button in the center of a ConstraintLayout to act as the orientation toggler.
2. Hide Title Bar programmatically:
   • In MainActivity.kt, call supportActionBar?.hide().
3. Apply Fullscreen Flags:
   • Retrieve the window reference and apply layout flags to hide status/navigation bars.
4. Implement Orientation Toggle Logic:
   • Bind a click listener to the button.
   • Check the current screen orientation via resources.configuration.orientation.
   • If it is Portrait (Configuration.ORIENTATION_PORTRAIT), set requestedOrientation to Landscape.
   • If it is Landscape, set requestedOrientation to Portrait.

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3. Implementation Code & Output

View Solution & Output

Layout File: res/layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#1E1E1E"
    tools:context=".MainActivity">

    <!-- Central Orientation Toggle Button -->
    <Button
        android:id="@+id/btnToggleOrientation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:text="Toggle Screen Orientation"
        android:textSize="16sp"
        android:backgroundTint="#FFBC3B"
        android:textColor="#1A1A37"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Activity File: src/main/java/com/example/fullscreenapp/MainActivity.kt

// 📱 VNSGU BCA Sem 3 - Mobile Application Development (Practical 305-2)
// 🚀 Action: Configure Fullscreen, hide title bar, and toggle orientation dynamically.

package com.example.fullscreenapp

import android.content.pm.ActivityInfo
import android.content.res.Configuration
import android.os.Build
import android.os.Bundle
import android.view.WindowInsets
import android.view.WindowInsetsController
import android.view.WindowManager
import android.widget.Button
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        // 1. Programmatic Title Bar Hiding
        supportActionBar?.hide()

        // 2. Programmatic Fullscreen Activation
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            // Modern API 30+ implementation
            window.insetsController?.let { controller ->
                controller.hide(WindowInsets.Type.statusBars() or WindowInsets.Type.navigationBars())
                controller.systemBarsBehavior = WindowInsetsController.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
            }
        } else {
            // Legacy implementation
            @Suppress("DEPRECATION")
            window.setFlags(
                WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN
            )
        }

        setContentView(R.layout.activity_main)

        // 3. Orientation Toggling Logic on Button Click
        val toggleButton: Button = findViewById(R.id.btnToggleOrientation)
        
        toggleButton.setOnClickListener {
            val currentOrientation = resources.configuration.orientation
            
            if (currentOrientation == Configuration.ORIENTATION_PORTRAIT) {
                // Change to Landscape
                requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
                Toast.makeText(this, "Switched to Landscape Mode", Toast.LENGTH_SHORT).show()
            } else {
                // Change to Portrait
                requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
                Toast.makeText(this, "Switched to Portrait Mode", Toast.LENGTH_SHORT).show()
            }
        }
    }
}

Manifest File: AndroidManifest.xml (Excerpt)

Ensure you add android:configChanges to your activity node. This tells the system that your activity will handle orientation changes itself, preventing the activity from restarting and reloading its state when the screen rotates:

<activity
    android:name=".MainActivity"
    android:exported="true"
    android:configChanges="orientation|screenSize|keyboardHidden">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

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💡 Common Examination Mistakes & Tips

Key Pitfalls to Avoid

1. Call order issues: Always call supportActionBar?.hide() or layout parameters before calling setContentView(R.layout.activity_main). Otherwise, the layout is drawn before settings are applied, which can lead to visual glitches.
2. No Configuration Handling: By default, Android restarts the current Activity when screen orientation changes. Always add android:configChanges="orientation|screenSize" to your activity inside AndroidManifest.xml to avoid data loss.
3. Modern vs Legacy APIs: Show knowledge of WindowInsetsController for SDK 30+ instead of relying solely on deprecated WindowManager flag settings.