Java-Enumeration interface summary details

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Enumeration ( Enumeration)Interfacehas a similar function to Iterator. It only provides the function of traversing the elements of Vector andHashTable type collections, and does not support the removal operation of elements.

The source code of the Enumeration interface in Java8:

public interface Enumeration { /** * Tests if this enumeration contains more elements. * * @return true if and only if this enumeration object * contains at least one more element to provide; * false otherwise. */ boolean hasMoreElements();//判断是否包含元素 /** * Returns the next element of this enumeration if this enumeration * object has at least one more element to provide. * * @return the next element of this enumeration. * @exception NoSuchElementException if no more elements exist. */ E nextElement();//获得下一个元素 }

According to the source code analysis of Enumeration, Enumeration has two methods:

(1) boolean hasMoreElements();// Whether there are still elements, if so, return true, otherwise it means that it contains at least one element

(2)E nextElement();//If the Enumeration enumerationobjectstill has elements, the returned object is only The next element that can be found, otherwise a NoSuchElementException is thrown.

Simple example:

public class TestEnumeration{ public static void main(String[] args){ Vector v = new Vector(); v.addElement("Lisa"); v.addElement("Billy"); v.addElement("Mr Brown"); Enumeration e = v.elements();//返回Enumeration对象 while(e.hasMoreElements()){ String value = (String)e.nextElement();//调用nextElement方法获得元素 System.out.print(value); } } }

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