Java EnumSet

Java EnumSet

Syntax:
java.lang.Object
        java.util.AbstractCollection
               java.util.AbstractSet
                      java.util.EnumSet

• The EnumSet collection from the java.util package.
• An EnumSet is a specialized Set collection to work with enum classes.
  
• The EnumSet is one of the specialized implementation of Set interface for use with the enumeration type. 
• The EnumSet class is a member of the Java Collections Framework & is not synchronized.
• It can contain only enum values and all the values have to belong to the same enum.
• It doesn't allow to add null values, throwing a NullPointerException in an attempt to do so.
• It’s a high performance set implementation, much faster than HashSet.

Methods:
How to create an empty EnumSet and add some elements?

• EnumSet of(E e1): Creates an enum set initially containing the specified elements.
• EnumSet of(E e11, E el2): Creates an enum set initially containing the specified elements.
• EnumSet of(E e11, E el2, Eel3): Creates an enum set initially containing the specified elements.
• EnumSet of(E e11, E el2, Eel3,E el4….): Creates an enum set initially containing the specified elements.
• EnumSet of(E e1, E rest…): Creates an enum set initially containing the specified elements.

Example:
//write this code after import libray
enum day
{
    SUN, MON, TUE, WED, THU, FRI, SAT
};
//write this code inside class
EnumSet set1;
set1 = EnumSet.of(day.SUN, day.MON, day.TUE, day.WED);

How to create complement set?
EnumSet complementOf(EnumSet s): Creates an enum set with the same element type as the specified enum set, initially containing all the elements of this type that are not contained in the specified set.

• Example:

EnumSet set2;
set2 = EnumSet.complementOf(set1);

How to insert all elements?
EnumSet allOf(Class elementType): Creates an enum set containing all of the elements in the specified element type.

• Example:

EnumSet set3;
set3 = EnumSet.allOf(day.class);

How to insert range of elements?
EnumSet range(E from, E to): Creates an enum set initially containing all of the elements in the range defined by the two specified endpoints.

• Example:

EnumSet set4:
set4 = EnumSet.range(day.MON, day.THU);

How to Check if the collection contains a specific element?

• Example: set1.contains(day.MON);

How to Iterate over the elements?

• Example:

set1.forEach(System.out::println);

How to remove simply remove elements?

• Example: set1.remove(day.TUE);

Other methods:

• EnumSet copyof(): The method is used to copy all of the contents from a collection to a new enum set.
• EnumSet copyof(EnumSet s): The method is used to copy all of the contents from an existing EnumSet to a new enum set.
• EnumSet clone(): The method is used to return a shallow copy of the existing or this set.
• EnumSet noneOf(): The method is used to create a null set.