Scala interview questions

• Mutable
• Immutable

By default, immutable map is supported by scala. To use the mutable map, the programmer needs to import the “scala.collection.mutable”. It is an explicit class. “mutable.map” is the syntax for using the mutable and immutable class in the same program. To access the immutable class, we just have to use the name of the map and it can be accessed.

• Nil- it is used to initialize an empty list since it is an object which extends list.
• Null- null in scala is used to provide compatibility with the java null keyword or to provide a type for the null keyword. It also represents the absence of type information for complex types.
• None- the “none” pattern in scala is used to remove null values from the scala code.
• Nothing- it is used for providing the return type for the operations that can affect the normal flow of program.

Instead of having static methods or variables, scala has singleton or companion objects. These objects are then compiled to classes which have static methods. Some advantages of these companion objects are listed below:

• These are beneficial as they can be used for encapsulating things. They also act as a bridge and hence functional and object-oriented programs can be written easily.
• These companion objects also help in keeping the scala programming code more concise because the static keyword need not be added to each and every attribute.
• A clear separation between the static and non-static methods is maintained with the help of these companion objects.