Enumeration in java

In this section you will learn about enumeration in java with example.

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Enumeration in java

In this section we will discuss about enumeration in java. Before getting details of enumeration, first we will describe about "enum" in java.  An "enum" is a data type that contain a set of predefined constants. The enum variable must equal to one of the values that is predefined. Example like weekdays, months of year etc. Because they are constants and the values of enum are in upper case. In Java you can define an enum by enum keyword.

public enum direction {NORTH, SOUTH, WEST, EAST}

To represent a fixed number of constant you should use enum. Here is some code that show you how to use enum :


public class Enum {
	
	public enum days {SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY,FRIDAY,SATURDAY};
public static void main(String args[])
{
	System.out.println("This is "+days.MONDAY);
	System.out.println("This is "+days.TUESDAY);
	System.out.println("This is "+days.WEDNESDAY);
	System.out.println("This is "+days.THURSDAY);
	System.out.println("This is "+days.FRIDAY);
  }
}

That will display the output as follows :

Download Source Code

Now, we will discuss about Enumeration in java. Enumeration is an interface in java which allows you to iterate or obtain one element at a time of collection. Enumeration can generate one element at a time, it is used for collection of unknown size. Traversing element of collection is done only once per creation. Enumeration has two methods they are as follows :

  • boolean hasMoreElement() : Returns true if collection has more element otherwise returns false when all element are traversed.
  • Object nextElement() : Return the next element in the collection.
Example
import java.util.Vector;
public class Enumeration {
	public static void main(String args[]) {
		Vector v = new Vector();
		v.add("North");
		v.add("East");
		v.add("West");
		v.add("South");
		java.util.Enumeration e = v.elements();
		System.out.println("Direction are :");
		while (e.hasMoreElements()) {
			System.out.println(e.nextElement());
		}

	}

}

Output : When you compile and run the program the output will be as follows :

Download Source Code

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