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Java in a Nutshell

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The java.util Package

30.6 java.util.Enumeration (JDK 1.0)

This interface defines the methods necessary to enumerate, or iterate through, a set of values, such as the set of values contained in a hashtable or binary tree. It is particularly useful for data structures, like hashtables, for which elements cannot simply be looked up by index, as they can in arrays. An Enumeration is usually not instantiated directly, but instead is created by the object that is to have its values enumerated. A number of classes, such as Vector and Hashtable, have methods that return Enumeration objects.

To use an Enumeration object, you use its two methods in a loop: hasMoreElements() returns true if there are more values to be enumerated, and can be used to determine whether a loop should continue. Within a loop, a call to nextElement() returns a value from the enumeration. An Enumeration makes no guarantees about the order in which the values are returned. The values in an Enumeration may be iterated through only once--there is no way to reset it to the beginning.

public abstract interface Enumeration {
    // Public Instance Methods
            public abstract boolean hasMoreElements();
            public abstract Object nextElement();

Implemented By:


Passed To:


Returned By:

AppletContext.getApplets(), Dictionary.elements(), Dictionary.keys(), FeatureDescriptor.attributeNames(), Hashtable.elements(), Hashtable.keys(), ListResourceBundle.getKeys(), MenuBar.shortcuts(), Properties.propertyNames(), PropertyResourceBundle.getKeys(), ResourceBundle.getKeys(), Vector.elements(), ZipFile.entries()

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