7. Marker interfaces, Singleton design pattern, why string is immutable

Question

Accepted Answer

Explaining marker interfaces, Singleton design pattern, and immutability of strings

Marker interfaces are interfaces with no methods, used to mark a class as having a certain behavior or capability
Singleton design pattern ensures only one instance of a class is created and provides a global point of access to it
Strings are immutable in Java to ensure their values cannot be changed once created, which improves security and performance
Immutable objects are thread-safe and can be safely shared among multiple threads
Examples of marker interfaces include Serializable, Cloneable, and Remote
Examples of Singleton design pattern include Logger, Configuration, and Database Connection
String immutability is enforced through final keyword and lack of setter methods

Top Mphasis Software Engineer Java/J2ee Spring Hibernate interview questions & answers