JAVA ENUM JAVA 8 STREAM | HOW TO ITERATE ENUM IN JAVA USING JAVA 8 STREAMS | CODE DEMO |InterviewDOT
Channel: Interview DOT
Date: 2021-06-06

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JAVA ENUM JAVA 8 STREAM | HOW TO ITERATE ENUM IN JAVA USING JAVA 8 STREAMS | CODE DEMO |InterviewDOT

Enums
An enum is a special "class" that represents a group of constants (unchangeable variables, like final variables).

To create an enum, use the enum keyword (instead of class or interface), and separate the constants with a comma. Note that they should be in uppercase letters:

Loop Through an Enum
The enum type has a values() method, which returns an array of all enum constants. This method is useful when you want to loop through the constants of an enum:

Difference between Enums and Classes
An enum can, just like a class, have attributes and methods. The only difference is that enum constants are public, static and final (unchangeable - cannot be overridden).

An enum cannot be used to create objects, and it cannot extend other classes (but it can implement interfaces).

Why And When To Use Enums?
Use enums when you have values that you know aren't going to change, like month days, days, colors, deck of cards, etc.
When should I use enum in Java?
Enums are lists of constants. When you need a predefined list of values which do represent some kind of numeric or textual data, you should use an enum. You should always use enums when a variable (especially a method parameter) can only take one out of a small set of possible values.

What is the use of enum class in Java?
A Java Enum is a special Java type used to define collections of constants. More precisely, a Java enum type is a special kind of Java class. An enum can contain constants, methods etc. Java enums were added in Java 5.

When would an enum or enumeration be used?
Enumerations offer an easy way to work with sets of related constants. An enumeration, or Enum , is a symbolic name for a set of values. Enumerations are treated as data types, and you can use them to create sets of constants for use with variables and properties.

Why do we use enum?
Enums are used when we know all possible values at compile time, such as choices on a menu, rounding modes, command line flags, etc. It is not necessary that the set of constants in an enum type stay fixed for all time. In Java (from 1.5), enums are represented using enum data type.

What are the disadvantages of enumerations?
Disadvantages of using Enum as a singleton:
Coding Constraints. In regular classes, there are things that can be achieved but prohibited in enum classes. Accessing a static field in the constructor, for example. ...
Serializability. For singletons, it is very common to be stateful.

How do you declare an enum?
An enum is defined using the enum keyword, directly inside a namespace, class, or structure. All the constant names can be declared inside the curly brackets and separated by a comma. The following defines an enum for the weekdays. Above, the WeekDays enum declares members in each line separated by a comma.

A Java Enum is a special Java type used to define collections of constants. More precisely, a Java enum type is a special kind of Java class. An enum can contain constants, methods etc. Java enums were added in Java 5.