Java Literacy Interface Enumeration

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I. Initial knowledge of enumeration

Two. Use of functions

Three. Demonstrating the use of the enumeration interface

I. Initial knowledge of enumeration

When I was writing network programming, I found this interface. It's amazing that none of them used to be, networkinterface.getnetworkinterfaces () returns the NetworkInterface object of the enumeration carrier. Enumeration is an interface class in Java.util that encapsulates methods for enumerating data collections in enumeration. The enumeration interface itself is not a data structure. However, it is important for other data structures. The enumeration interface defines the means by which continuous data is obtained from a data structure.

Note: The functionality of this interface is duplicated with the functionality of the Iterator interface. Additionally, the Iterator interface adds an optional remove operation and uses a shorter method name. The new implementation should prioritize the use of the Iterator interface instead of the enumeration interface. Two. Use of the function Java.util enumeration<e>

All elements in a vector are usually printed with the following two methods in enumeration:

(1)boolean hasMoreElements()
Tests whether this enumeration contains more elements.

(2)E nextElement()
If this enumeration object has at least one element that can be supplied, the next element of this enumeration is returned.

Usage One:

VEC is an object of the interface implementation class vector (collection), and Vec.elements () obtains an element of the vector (collection).

 for (Enumeration e = vec.elements (); e.hasmoreelements ();) {

}

Usage Two:

E is a object that implements the enumeration interface

 while (E.hasmoreelements ()) {    Object o= e.nextelement ();    System.out.println (o);}

Here's an example:

 Public classtestenumeration{ Public Static voidMain (string[] args) {Vector v=NewVector (); V.addelement ("Li"); V.addelement ("YYY"); V.addelement ("Brown"); Enumeration e=v.elements ();  while(E.hasmoreelements ()) {String value=(String) e.nextelement ();              System.out.println (value); }       }}

You can see the following output

Liyyybrown

Three. Demonstrating the use of the enumeration interface

Here we implement this interface to complete a small function:

The Mydatastruct class is used to instantiate a simple, enumeration object that can be supplied to a data result object that uses the program

Class mydatastruct{    string[] data;    Constructor    mydatastruct ()    {        data = new String[4];        Data[0] = "zero";        DATA[1] = "one";        DATA[2] = "both";        DATA[3] = "three";    }    Returns a enumeration object to the user program    enumeration getenum ()    {        return new myenumeration (0, Data.length, data);}    }

　　

Myenumeration class implements enumeration interface

classMyenumerationImplementsenumeration{intCount//counter    intLength//the length of the stored arrayObject[] DataArray;//storing a reference to an array of data//ConstructorsMyenumeration (intCountintlength, object[] dataarray) {         This. Count =count;  This. length =length;  This. DataArray =DataArray; }     Public Booleanhasmoreelements () {return(Count <length); }     PublicObject nextelement () {returndataarray[count++]; }}

Test class MainClass

classmainclass{ Public Static voidMain (string[] args) {//instantiating an object of type MydatastructMydatastruct mysatastruct =Newmydatastruct (); //Gets the enumeration object that describes the Mydatastruct type ObjectEnumeration myenumeration =Mysatastruct.getenum (); //use an object loop to display each element in an object of type Mydatastruct         while(Myenumeration.hasmoreelements ()) System.out.println (Myenumeration.nextelement ()); }}

You can see the following output:

Zeroonetwothree

Four. Thanks to the source of knowledge and summary

I. Initial knowledge of enumeration

Two. Use of functions

Three. Demonstrating the use of the enumeration interface

From: Java Basics

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