Java Enum FAQ - What Every Java Developer should know most Enumeration type

Java Enum was ane of the best features added on JDK 1.5 Tiger liberate along amongst Generics, Autoboxing, in addition to varargs. Enum inwards Java represents fixed number of well-known things e.g. number of days inwards Week, the number of months inwards the calendar twelvemonth etc. Unlike C in addition to C++ Enum inwards Java are much powerful in addition to they are non an integer constant, Instead, Enum is a Type similar cast or interface which provides compile fourth dimension type safety. In this Java Enum tutorial, nosotros volition come across a yoke of of import points close Java Enum which assistance to sympathise Enum ameliorate in addition to acquire most out of it. I accept written inwards the mode of FAQ i.e. oft asked questions, this volition assistance you lot to larn to a greater extent than close Java Enum's capability in addition to features e.g. whether Enum tin extend cast or implement methods or not? When you lot tin override methods within enum? whether you lot tin compare Enum using equals() or == inwards Java? etc

Java Enum FAQ - Frequently asked Questions

As I told you lot enum or enumeration type inwards Java is ane of the of import concepts inwards Java. It's non merely plenty to larn close cast in addition to interface, you lot too accept to larn close Enumeration type. In this article, I volition response to a greater extent than or less of the oft asked questions based upon Java Enum, these volition assistance you lot to larn the concept ameliorate in addition to motivate you lot to explore yesteryear yourself.

What is Enum inwards Java?

Enum is Java build much similar a cast in addition to interface which is used to correspond fixed number of well-known things e.g. days of the week, months of a twelvemonth etc.

What is the role of Enum inwards Java?

As I told inwards the previous example, you lot tin role Enum to correspond fixed number of things e.g. you lot tin role it correspond the states of your application e.g. threads states similar Runnable, Running, Stopped etc. You tin too role it to implement Strategy pattern. You tin role Enum to write thread-safe Singleton, in addition to fifty-fifty to exercise your ain acre car inwards Java.

What is the deviation betwixt C, C++ enum in addition to Java Enum?

Unlike C in addition to C++, Enum inwards Java are non integer constant, they are classes, similar to whatever interface or class. Because of this argue Enum inwards Java provides type safety in addition to compile time checking which was non possible amongst enum int pattern. Java Enum is a full-fledged type in addition to you lot tin role it equally cast or interface.

Can Enum extend a Class inwards Java?
No, Enum cannot extend a Class inwards Java. Every Enum inwards Java extends from java.lang.Enum implicitly in addition to because of this Enum tin non extend whatever other cast inwards Java.

Can Enum accept Constructor inwards Java?

Enum inwards Java doesn't accept a world constructor. This way you lot tin non exercise an additional representative of Enum instances other than what is created from Enum cast itself in addition to available at compile time. Enum tin accept a private constructor, though.

Can you lot declare methods within Enum inwards Java?
Yes, you lot tin declare methods inwards Java Enum in addition to you lot tin even override in addition to overload them within private Enum instances. For example, you lot accept declared a Color enum which has a method getHexCode(). Now, you lot declare 4 colors or enum constants inwards Color enum e.g. RED, BLUE, GREEN, WHITE, BLACKand thence you lot tin override getHexCode() method to render hex code for these color e.g. RED volition render 0xFF0000 in addition to BLACK volition render 0x000000.

You tin farther read Core Java, Volume 1 - Fundamentals yesteryear Cay S. Horstmann to larn to a greater extent than close advanced features of Enum inwards Java.

Can you lot modify the value of Enum representative inwards Java?

Enum values or Enum instances are public, static in addition to final inwards Java. They are a compile-time constant, which way you lot tin non changes values of Enum instances in addition to farther assignment volition number inwards compile fourth dimension error.

Can Enum implement an interface in addition to override method inwards Java?

Yes, Enum inwards Java tin implement interface in addition to override methods. In fact, Java Enum implicitly implements Comparable interface in addition to override compareTo() method. You tin cheque the code of java.lang.Enum cast to confirm this.

How to compare 2 Enumeration inwards Java?
Enum representative inwards Java tin last compared using == equality operator or equals() method inwards Java. Enum provides the high-quality implement for equals() in addition to hashCode in addition to tin last used inwards Set in addition to Map. But for functioning reason, it's best to role EnumMap in addition to EnumSet piece storing enum inwards Collection.

How to compare same instances of the same Enum inwards Java?

When you lot compare dissimilar instances of the same Enum type, they are compared inwards the social club on which they are declared inwards Enum. You tin acquire this social club yesteryear calling the ordinal() method of Enum.

Java Enum was ane of the best features added on JDK Java Enum FAQ - What Every Java Developer should know close Enumeration type

How to convert Enum to String inwards Java?

Enum provides implicit methods similar values(), ordinal() in addition to name() which tin last used to acquire all Enum instances equally an array, social club of enum equally declared inwards cast in addition to String cite of Enum instances inwards Java.

How to convert Enum to Array inwards Java?
You tin role Enum's values() to convert an Enum to array inwards Java. This method returns an array containing all Enum constants. See these examples to larn to a greater extent than close how to role values() method of java.lang.Enum inwards Java.

How to iterate over Enum inwards Java?

You tin role Enum's values() method tin last used to iterate over enum. It returns an array which tin last traversed using whatever loop constructs inwards Java, including Java 1.5 enhanced for loop.

That's all close to a greater extent than or less frequently asked questions close Enumeration type inwards Java. Enum is much powerful in addition to they accept used inwards dissimilar ways inwards Java programming language. you lot tin fifty-fifty role Enum to exercise thread-safe Singleton inwards Java. You tin too supervene upon your onetime code which is written using enum int blueprint or enum String blueprint inwards Java.

If you lot accept whatever questions related to Enum inwards Java thence delight drib a comment in addition to I'll seek to response your questions. If you lot desire to larn to a greater extent than you lot tin farther read Head First Java, it explains Enum concepts quite well.

References
https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html
Effective Java yesteryear Joshua Bloch