THE PACKAGE JAVA.UTIL

java.util.Enumeration

21.1

21.1 The Interface

java.util.Enumeration

An object that implements the

Enumeration

 interface will generate a series of

elements, one at a time. Successive calls to the

nextElement

 method will return

successive elements of the series.

public interface Enumeration {

public boolean hasMoreElements();

public Object nextElement() throws NoSuchElementException;

}

21.1.1

public boolean hasMoreElements()

The result is

true

 if and only if this enumeration object has at least one more ele 

ment to provide.

21.1.2

public Object nextElement()

throws NoSuchElementException

If this enumeration object has at least one more element to provide, such an ele 

ment is returned; otherwise, a

NoSuchElementException

 is thrown.

As an example, the following code prints every key in the hashtable

ht

 and its

length. The method

keys

 returns an enumeration that will deliver all the keys, and

we suppose that the keys are, in this case, known to be strings:

Enumeration e = ht.keys();

while (e.hasMoreElements()) {

String key = (String)e.nextElement();

System.out.println(key + " " + key.length());

}

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