Update MainActivity.java

[prashant152005]

Here are some improvements for better readability, maintainability, and adherence to modern Android practices, while preserving the primary functionality of the code:

1. Refactor Code Structure: Organize methods and variables logically. Group related methods together and make the code more modular.
2. Replace Deprecated Libraries: Migrate away from deprecated libraries like android.support.v4 and android.support.v7. Use androidx libraries instead.
3. Improve Readability: Add comments, use more descriptive variable names, and simplify complex statements.

Key Changes:

1. Updated Imports: Moved from android.support to androidx.
2. Code Organization: Grouped similar methods together and added helper methods for clarity.
3. Descriptive Methods: Renamed some methods for clarity and simplicity.
4. Removed Deprecated Methods: Updated deprecated methods and practices.