Member Research & Development Interview Questions and Answers

Implementing interfaces vs abstract classes in real life

• Interfaces are useful when implementing multiple inheritance in Java

• Abstract classes are useful when creating a base class with some implementation

• Example of interface: implementing Runnable interface in a class to create a thread

• Example of abstract class: creating a base class for different types of vehicles

Singleton pattern ensures only one instance of a class is created and provides a global point of access to it.

• Private constructor to restrict object creation

• Private static instance variable to hold the single instance

• Public static method to get the instance

• Lazy initialization or eager initialization

• Thread-safe implementation using synchronized keyword or static block

• Examples: java.lang.Runtime, java.awt.Desktop, java.util.Calendar

Sort map entries based on value

• Use a TreeMap to sort the entries based on value

• Implement a Comparator to compare the values

• Convert the TreeMap to a LinkedHashMap to maintain the order of insertion

SOLID design principles are a set of guidelines for writing maintainable and scalable code.

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

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

• L - Liskov Substitution Principle: Subtypes should be substitutable for their base types.

• I - Interface Segregation Principle: A client should not be forced to depend on methods it does not use.

• D - Dependency Invers...read more