Android Engineer Interview Questions and Answers

Determine the minimum number of operations needed to make a binary string beautiful by having alternating 0s and 1s.

• Iterate through the binary string and count the number of operations needed to make it beautiful by flipping the bits if they are the same.

• Keep track of the current bit and compare it with the next bit to determine if an operation is needed.

• Return the total number of operations needed for each test case.

Find the rectangle within a matrix that has the maximum sum of its elements.

• Iterate through all possible rectangles within the matrix

• Calculate the sum of each rectangle

• Keep track of the maximum sum found

Reverse nodes within blocks of specified sizes in a singly linked list.

• Iterate through the linked list and reverse nodes within each block size specified in the array.

• Handle cases where block size exceeds remaining nodes by reversing the remaining nodes as one block.

• Update pointers accordingly to reverse the nodes within each block size.

There are three main architecture patterns in Android: Model-View-Controller (MVC), Model-View-Presenter (MVP), and Model-View-ViewModel (MVVM).

• Model-View-Controller (MVC) separates the application into three main components: the model (data), the view (UI), and the controller (logic).

• Model-View-Presenter (MVP) separates the application into three main components: the model (data), the view (UI), and the presenter (handles user input and updates the view).

• Model-View-ViewModel...read more

Room library is a persistence library that provides an abstraction layer over SQLite to allow for more robust database access while leveraging the full power of SQLite.

• Room library simplifies database interactions by providing compile-time verification of SQL queries.

• It includes components like Entity, DAO (Data Access Object), and Database to define database schema and access data.

• Room library also supports LiveData and RxJava for reactive programming with databases.

• Example:...read more

SOLID principles are a set of five design principles in object-oriented programming to make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable with objects of its subclasses without affecting the func...read more

Coroutines are lightweight threads that can be suspended and resumed, allowing for asynchronous programming in Kotlin.

• Coroutines are defined using the 'suspend' keyword in Kotlin.

• They can be launched using 'launch' or 'async' functions from the kotlinx.coroutines library.

• Coroutines can suspend execution using 'delay' or other suspension points.

• They can communicate with each other using channels or other forms of structured concurrency.