Enum or Enumeration in Java is a set of pre-defined named values which is separated by commas. The values in Enum are always constant. So the Enum values must be represented in UPPERCASE only. When we need a pre-defined set of constant values, days in a week or seasons of a year, etc, we use Enum. Enum is considered a special class because of the following characteristics:
- The Enum constants cannot be overridden
- Enum does not support the creation of separate objects
- Enum cannot extend to other objects
- Enum can implement interfaces like the classes
In Java, the enum type is not defined as class or interface. The keyword enum is used instead of class or interface.
For example: enum Variable_Name {VALUE1, VALUE2,……}
The Properties of Enum include the addition of fields, constructors, and methods by the users. It can also implement interfaces. The compilers will not allow the users to completely extend the enum class.
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Advantages of Java Enum
Java enumerations give a lot of advantages to its users. Enum is supported by Java 5. It is a predefined set of named values that are separated by commas. In java enum, the users can add methods, fields, etc. The advantages of Java Enum include:
- Type Safety – Enums provides type – safety at the time of compiling. This helps in the prevention of comparing the constants in different enums.
- Limit Inputs – In a switch statement where the enum is used, the only allowed labels for cases are the enum constants. The use of IDE eclipse helps in the auto-completing feature for filling them.
- Group Things- Enum group things are a set
- Iterable – One of the main advantages of Java enum is that it is iterable.
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Java Enum Features
Java enum is a feature provided by the Java 5 version to the developers. Enum or Enumerations by Java is constant and it provides many features to the developers. Let us look at some of the features provided by Java enum.
- Constant
Enum provided by Java is constant. They are unconditionally declared public static and final. These enums are constant and the users cannot change these enums.
All enum types are extended from java. lang.enum class. This represents that the enum is a class type. Moreover, the enum constants are examples of enumeration class.
- Enum and classes
We have said all enum types extend from java. lang. enum class, these cannot be extended to any other classes in java. This is because multiple endowments are not allowed in java. A class can only extend to one class.
- Enum and Interface
Java enum can implement interfaces. Implementing an interface is also a method to extend the enum type.
- Enum and Constructor
An enum class can have a constructor. The constructor of the enum class must be private. Why the constructor cannot be made public because the enum instances are meant to be created at the time of compiling and from the class itself.
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Enum Methods
There are many enum methods are used to write. Let us look at some of the enum methods where the object methods are overridden. The importance of these methods are they are declared as final and they cannot be overridden in a subclass. They are:
- clone() – This method is used to prevent the constants from making a copy or clone.
- equals() – This method is used to compare the constants with the help of the respective references.
- finalize() – This method is used to make sure that the constants cannot be finalized
- hashCode() – This method is used because the equals are overridden.
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Conclusion
Java enumeration types are an important feature provided by the Java 5 version. This feature is still in the run-in many versions. The enumeration types give many advantages to the users and it increases productivity also.
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