Android Architecture and Lifecycle Quiz

Study Notes

Android Architecture

Android architecture consists of four main layers: Linux Kernel, Hardware Abstraction Layer, Android Runtime, and Application Framework.
Linux Kernel provides core system services like security and memory management.
Hardware Abstraction Layer simplifies interactions between Android and hardware.
Android Runtime includes libraries and frameworks like ART, which executes applications.
Application Framework provides higher-level services to applications, such as activity management, resource management, and notifications.

Activity Life Cycle

The Activity Life Cycle comprises various states that an activity can be in: Created, Started, Resumed, Paused, Stopped, and Destroyed.
Transition states govern how activities interact with the user and system resources.
Flowchart illustrates transitions: onCreate() → onStart() → onResume() → onPause() → onStop() → onDestroy().

Service in Android

A Service is a component that runs in the background to perform long-running operations without a user interface.
Difference: Activities are UI components allowing user interaction; Services run in the background without direct interaction.

Intent in Android

An Intent is a messaging object used to request an action from another app component.
Explicit Intents specify the target component (e.g., opening a specific activity).
Implicit Intents do not name a specific component, allowing the system to find suitable handlers (e.g., opening any activity that can handle a web link).

Code Example for Implicit Intent

Use an Intent to send data from one activity to another, such as:

Intent intent = new Intent(Intent.ACTION_SEND);
intent.putExtra(Intent.EXTRA_TEXT, "Data to send");
startActivity(Intent.createChooser(intent, "Send Data"));

Code Example for Sending Email

Implement an explicit intent to send an email:

Intent emailIntent = new Intent(Intent.ACTION_SENDTO);
emailIntent.setData(Uri.parse("mailto:"));
emailIntent.putExtra(Intent.EXTRA_SUBJECT, "Subject");
emailIntent.putExtra(Intent.EXTRA_TEXT, "Email body");
if (emailIntent.resolveActivity(getPackageManager()) != null) {
    startActivity(emailIntent);
}

Fragment in Android

A Fragment is a modular section of an activity that can have its own lifecycle and receive its own input events.
Example: A multi-pane UI in tablets can use fragments to display lists and details simultaneously.

Available Layouts in Android

Common layouts include LinearLayout, RelativeLayout, ConstraintLayout, FrameLayout, and TableLayout.
Each layout serves different UI arrangement purposes, promoting flexible designs.

Code to Display Toast Message

Toast is a simple message that pops up on the screen.

Toast.makeText(getApplicationContext(), "Button Clicked", Toast.LENGTH_SHORT).show();

Tab Layout, RecyclerView, and Card View

Tab Layout allows users to switch between different views or fragments quickly.
RecyclerView is an advanced version of ListView, efficiently displaying large data sets with view holders.
Card View presents information in card layouts, enhancing UI aesthetics while providing a consistent design.

Shared Preferences

Shared Preferences store key-value pairs of primitive data types and are used for saving simple app settings.
Example: Saving user preferences like themes or login status.

Content Provider

Content Providers manage access to a structured set of data by other applications.
They allow data sharing between apps and use URIs to identify specific data.

SQLite Database

SQLite is a lightweight database used in Android for managing structured data.
Required for data persistence, supports complex queries, and offers transactions.

Code for SQLite Connection

Establish a connection with SQLite database:

SQLiteDatabase db = this.getWritableDatabase();

Significance of onCreate() and onUpgrade()

onCreate() initializes the database, creating tables.
onUpgrade() handles database schema changes, such as modifying or deleting tables.

Student Registration Application

Develop an app that collects basic student information: name, enrollment number, branch, address, and mobile number.
Utilize input forms to gather and store data in SQLite.

Movie Ticket Booking Application Steps

Design the application to allow users to search movies, select showtimes, and book tickets.
Implement various screens for user interactions and backend database handling.

Code for DCIM Folder Files

Fetch and print files stored in the DCIM folder:

File dcimFolder = new File(Environment.getExternalStorageDirectory(), "DCIM");
File[] files = dcimFolder.listFiles();
for (File file : files) {
    Log.d("File Name", file.getName());
}

Code for Inserting Customer Details

Insert customer information (cID, cName, cOrderID) into SQLite Database:

ContentValues values = new ContentValues();
values.put("cID", id);
values.put("cName", name);
values.put("cOrderID", orderId);
db.insert("Customers", null, values);