An enumeration in Java is a class
type. It can have constructors, instance variables of enumeration can be
declared, you can define methods in an enumeration, one enumeration can inherit
the other and it can also implement interfaces.
Points to remember when
using Enumerations
1. You can’t instantiate an enum using new.
2. Every enumeration constant is an
object of its enumeration type.
3. You can define a constructor for an enum, this constructor is called only
after each enumeration constants are created.
Important two methods
of enumerations
1. The
values () method: It returns the list of enumeration
constants in the form of an array.
The general form of method is as
shown below.
public static enum-typeName[] values()
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2. The
valuesOf () method: It returns the enumeration constant
whose value corresponds to the string passed to the method.
The general form of method is as shown below.
public static enum-typeName valuesOf(String str)
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Consider the
below program example that shows enumeration is a class type and also
illustrates the use of the above mentioned two methods.
package blog.enumeration;
public enum StudentNames
{
Rama(21),Shama(18),Ravi(20);
private int age;
StudentNames(int age)
{
this.age=age;
}
int ageOfStudent()
{
return age;
}
}
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package blog.enumeration;
public class StudentNameEnumDemo
{
public static void main(String[] args)
{
StudentNames
name;
// display the name and age of particular student.
name=StudentNames.valueOf("Ravi");
int age=StudentNames.Ravi.ageOfStudent();
System.out.println(name+"'s age is "+age);
System.out.println();
// display the list of names in Enum and their ages.
for(StudentNames names:StudentNames.values())
System.out.println(names+"'s age is "+names.ageOfStudent());
}
}
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Output:
Ravi's age is 20
Rama's age is 21
Shama's age is 18
Ravi's age is 20
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