Added in API level 1

Enumeration

public interface Enumeration

java.util.Enumeration<E>


An object that implements the Enumeration interface generates a series of elements, one at a time. Successive calls to the nextElement method return successive elements of the series.

For example, to print all elements of a Vector<E> v:

   for (Enumeration<E> e = v.elements(); e.hasMoreElements();)
       System.out.println(e.nextElement());

Methods are provided to enumerate through the elements of a vector, the keys of a hashtable, and the values in a hashtable. Enumerations are also used to specify the input streams to a SequenceInputStream.

Summary

Public methods

default Iterator<E> asIterator()

Returns an Iterator that traverses the remaining elements covered by this enumeration.

abstract boolean hasMoreElements()

Tests if this enumeration contains more elements.

abstract E nextElement()

Returns the next element of this enumeration if this enumeration object has at least one more element to provide.

Public methods

asIterator

Added in API level 33
public Iterator<E> asIterator ()

Returns an Iterator that traverses the remaining elements covered by this enumeration. Traversal is undefined if any methods are called on this enumeration after the call to asIterator.

API Note:
  • This method is intended to help adapt code that produces Enumeration instances to code that consumes Iterator instances. For example, the JarFile.entries() method returns an Enumeration<JarEntry>. This can be turned into an Iterator, and then the forEachRemaining() method can be used:
    JarFile jarFile = ... ;
         jarFile.entries().asIterator().forEachRemaining(entry -> { ... });
     
    (Note that there is also a JarFile.stream() method that returns a Stream of entries, which may be more convenient in some cases.)
Implementation Requirements:
  • The default implementation returns an Iterator whose hasNext method calls this Enumeration's hasMoreElements method, whose next method calls this Enumeration's nextElement method, and whose remove method throws UnsupportedOperationException.
Returns
Iterator<E> an Iterator representing the remaining elements of this Enumeration

hasMoreElements

Added in API level 1
public abstract boolean hasMoreElements ()

Tests if this enumeration contains more elements.

Returns
boolean true if and only if this enumeration object contains at least one more element to provide; false otherwise.

nextElement

Added in API level 1
public abstract E nextElement ()

Returns the next element of this enumeration if this enumeration object has at least one more element to provide.

Returns
E the next element of this enumeration.

Throws
NoSuchElementException if no more elements exist.