Mobile Application Development Mid EXAM paper solution
Subject Name: Mobile Application Development | ||||
Subject Code: 3161612 | ||||
Q-1 | A | Explain AndroidManifest.xml file. The AndroidManifest.xml file is a fundamental part of any Android application. It acts like a blueprint, telling the Android system everything it needs to know about your app, including its structure, components, and requirements. Here's a breakdown of its key functions: 1. Declaring App Components: The manifest file defines the building blocks of your app, which include:
2. Permissions Management: The manifest file is where you specify the permissions your app needs to function. This could be access to the camera, location, or storage. It ensures your app only accesses resources it has permission for. 3. Specifying API Level Requirements: The manifest file allows you to declare the minimum Android API level your app requires to run. This ensures compatibility with different Android versions. 4. Other Configurations: In addition to the above, the manifest file can also be used to:
Overall, the AndroidManifest.xml file is a critical piece of code that serves as the introduction to your app for the Android system. It provides all the essential details the system needs to run your app smoothly and securely. | 3 | |
B | What is Intent? Explain with suitable examples. In Android development, an Intent is a messenger that acts as a communication channel between different components of your app or even between your app and the entire Android system. It's like a way to express what you want to happen without directly calling a specific method. Analogy: Imagine you're at a restaurant (your app) and you want fries (another app component or functionality). Instead of yelling out to the kitchen (directly calling a method), you tell your waiter (the Intent) what you want. The waiter then delivers the message (Intent) to the kitchen (app component), which fulfills your request (starts the service to make fries). Types of Intents: There are two main types of Intents:
Java Intent viewProductDetails = new Intent(this, ProductDetailsActivity.class); startActivity(viewProductDetails); Use code with caution. content_copy
Java Intent openWebpage = new Intent(Intent.ACTION_VIEW, Uri.parse("https://www.example.com")); startActivity(openWebpage); Use code with caution. content_copy Benefits of Intents:
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Q-2 | A | What are the advantages of using fragments over activities? Here are three key advantages of using fragments over activities:
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B | Write a note on: “Android Framework”. The Android Framework: Foundation for Android AppsThe Android framework is the cornerstone of Android application development. It's a collection of pre-written components and APIs (Application Programming Interfaces) that provide the building blocks for creating feature-rich Android apps. Here's a closer look at its key aspects: 1. Core Components: At the heart of the framework lies a layered architecture with essential components:
2. Functionality and APIs: The framework offers a rich set of APIs that developers can leverage to:
3. Benefits of Using the Framework: Utilizing the Android framework provides several advantages:
4. Open Source and Extensible: The Android framework is open-source, allowing developers to contribute and customize it for specific needs. Additionally, libraries and extensions can further enhance the functionalities available to developers. 5. Learning Resources: Android provides extensive documentation and tutorials to help developers learn and leverage the framework effectively. This fosters a strong developer community and facilitates knowledge sharing. In conclusion, the Android framework is an indispensable tool for Android app development. By understanding its components, functionalities, and advantages, developers can create robust, efficient, and user-friendly applications. | 7 | ||
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Q-2 | A | Explain DVM. DVM, standing for Dalvik Virtual Machine, was a core component in earlier versions of Android (pre-Lollipop). It functioned as a virtual machine designed specifically for resource-constrained mobile devices. Here's a quick explanation:
In short, DVM was a virtual machine that powered Android apps in earlier versions of the OS. While it's no longer the primary execution environment, understanding its role provides historical context for Android development. | 3 | |
B | Write a note on: Activity Life Cycle The Activity lifecycle in Android development is the foundation for understanding how screens (Activities) are created, managed, and destroyed within your application. Grasping this lifecycle is essential for building responsive and efficient Android apps. Stages of the Activity Lifecycle: An Activity goes through various stages throughout its lifetime. Here's a breakdown of these stages with explanations and code examples:
Java @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Find view elements by ID (e.g., Button button = findViewById(R.id.myButton);) // Set up click listeners or other event handlers } }
onStart(): This method is invoked when the Activity becomes visible to the user. This is a good time to start animations or make visual changes to the UI. protected void onStart() { super.onStart(); // Start animations or other visual changes }
onResume(): This method signifies that the Activity is now in the foreground and fully interactive with the user. This is where most user interactions and core functionalities of the Activity take place. protected void onResume() { super.onResume(); // Activity is now active and ready for user interaction }
onPause(): This method is called when the Activity loses focus but remains partially visible. This could happen when another Activity is launched on top of it. In onPause(), you can pause any ongoing processes or animations to conserve resources. protected void onPause() { super.onPause(); // Pause animations or ongoing processes }
onStop(): This method is triggered when the Activity is no longer visible to the user. It's recommended to stop any background tasks or resource-intensive operations here to improve performance. protected void onStop() { super.onStop(); // Stop background tasks or resource-intensive operations }
onDestroy(): This method is called just before the Activity is completely destroyed. You can use this opportunity to clean up resources like database connections or unregister receivers to prevent memory leaks. protected void onDestroy() { super.onDestroy(); // Clean up resources like database connections, unregister receivers
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Q-3 | A | Explain Checkbox with an example. Checkboxes in Android: User Input with Two StatesA checkbox is a UI element that allows users to select one or more options from a set of choices. It's a small square box that gets marked (ticked) or unchecked, indicating the user's selection. Checkboxes are commonly used in Android applications for:
Creating a Checkbox:
XML <CheckBox android:id="@+id/my_checkbox" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Remember me" /> Use code with caution. content_copy
Java CheckBox checkBox = findViewById(R.id.my_checkbox); // Set checked state programmatically checkBox.setChecked(true); // Checkbox is ticked // Get checked state boolean isChecked = checkBox.isChecked(); // Set a listener for checkbox clicks checkBox.setOnCheckedChangeListener(new OnCheckedChangeListener() { @Override public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { // Handle checkbox click events (checked or unchecked) if (isChecked) { // Checkbox is checked, perform actions } else { // Checkbox is unchecked, perform actions } } }); | 4 | |
B | List out various layouts available in Android. Explain any one with an xml code file. Here's a list of various layouts available in Android along with an explanation and code example for LinearLayout: Layouts in Android: Android offers a variety of layouts to structure your app's user interface (UI). These layouts act as containers for your UI elements like buttons, text views, images, and more. Here are some common layouts:
LinearLayout: A Simple and Flexible Layout LinearLayout is a fundamental layout that organizes views in a single line, either horizontally (using android:orientation="horizontal") or vertically (the default). It's a versatile layout for many UI elements and is relatively easy to use. Here's an example of a LinearLayout in an XML layout file (activity_main.xml): XML <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:id="@+id/text_view_label" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Enter your name:" /> <EditText android:id="@+id/edit_text_name" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="Enter your name" /> <Button android:id="@+id/button_submit" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Submit" /> </LinearLayout> Use code with caution. content_copy Explanation:
This is a basic example, but it demonstrates how LinearLayout can be used to arrange UI elements in a simple and organized manner. You can add more child elements and customize their attributes to create more complex layouts. | 7 | ||
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Q-3 | A | Explain Date and Time picker with its methods. Here's a breakdown of the DatePicker methods and attributes you mentioned, along with explanations and additional points: DatePicker Methods:
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B | Give a brief idea about Internal versus External storage. Here's a breakdown of the key differences between Internal and External storage in Android: Internal Storage:
External Storage:
In simpler terms:
Additional Points:
Demonstrating how to use Internal Storage and External Storage in Android: Internal Storage: Java // Get internal storage directory File internalStorageDir = getFilesDir(); // Create a file within internal storage (replace "myfile.txt" with your filename) File internalFile = new File(internalStorageDir, "myfile.txt"); // Write data to the file (replace "This is internal storage data" with your data) try { FileOutputStream outputStream = new FileOutputStream(internalFile); outputStream.write("This is internal storage data".getBytes()); outputStream.close(); } catch (IOException e) { e.printStackTrace(); } // Read data from the file try { FileInputStream inputStream = new FileInputStream(internalFile); StringBuilder data = new StringBuilder(); int c; while ((c = inputStream.read()) != -1) { data.append((char) c); } inputStream.close(); Log.d("Internal Storage", data.toString()); // Print data to logcat } catch (IOException e) { e.printStackTrace(); } External Storage (Checking Availability): Java // Check if external storage is available for read/write boolean isExternalStorageWritable = Environment.getExternalStorageState() == Environment.MEDIA_MOUNTED; if (isExternalStorageWritable) { // Get external storage directory (replace "STORAGE_DIRECTORY" with your desired folder name) File externalStorageDir = new File(Environment.getExternalStorageDirectory(), "STORAGE_DIRECTORY"); // Create a file within external storage (replace "myfile.txt" with your filename) File externalFile = new File(externalStorageDir, "myfile.txt"); // Similar logic as internal storage for writing and reading data // ... (code omitted for brevity) } else { // Handle the case where external storage is not available Log.w("External Storage", "External storage not writable!"); } } Important Note:
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