Java Quiz

Which Java collection does not allow duplicate elements?

• HashSet

• ArrayList

• LinkedList

• TreeMap

Which Java collection allows access to elements using index-based methods?

• Set

• Queue

• Map

• List

Which Java collection ensures that elements are stored in ascending order based on their natural ordering or a custom comparator?

• HashMap

• TreeSet

• LinkedHashMap

• HashSet

What interface in Java Collection Framework allows you to store key-value pairs?

• Set

• List

• Map

• Collection

Which is the root interface used for storing elements and provides methods to manipulate them?

• List

• Map

• Collection

• Set

Which Java collection guarantees insertion order?

• HashSet

• TreeMap

• LinkedHashMap

• HashMap

Which Java collection class provides a resizable array implementation?

• HashSet

• ArrayList

• HashMap

• LinkedList

Which of the following is NOT a primitive data type in Java?

• int

• float

• double

• String

What happens when you concatenate a String with a primitive data type in Java?

• The primitive data type is automatically converted to a String before concatenation.

• The primitive data type remains unchanged.

• 
  An error occurs because primitive data types cannot be concatenated with Strings.

• The primitive data type is converted to its corresponding object wrapper class before concatenation.

What does the == operator compare when used with reference types in Java?

• It compares the contents of the objects.

• It compares the memory addresses of the objects.

• it compares the sizes of the objects.

• It compares the types of the objects.