枚举是一个接口。在Java中的集合框架中使用它来一一检索元素。枚举是一个遗留接口，仅适用于 Vector、HashTable、Stack 等遗留类。它提供单向迭代。通过枚举，我们只能执行读操作，不能执行移除操作。
枚举对象可以通过调用 Vector 类中的 elements() 方法来创建。
// Here "v" is a vector object. enum is of
// type Enumeration interface and refers to "v"
Enumeration enum = v.elements();
迭代器是可以应用于任何集合对象的通用游标。它提供单方向迭代。通过使用迭代器，我们可以执行读取和删除操作，但不能执行替换操作。每当我们想要枚举所有集合框架实现的接口(如 Set、List、Queue、DeQue 以及 Map 接口的实现类)中的元素时，都必须使用迭代器。
可以通过调用 Collection 接口中的 iterator() 方法来创建迭代器对象
// Here "c" is any collection object. itr is of
// type Iterator interface and refers to "c"
Iterator itr = c.iterator();
ListIterator是所有三个游标中功能最强大的游标。 ListIterator 仅适用于列表实现的类，如 ArrayList、LinkedList、Stack 等。 ListIterator 向前和向后遍历。通过使用 ListIteartor，我们可以执行读取、删除和替换操作。当我们想要枚举列表的元素时，必须使用 ListIterator。
ListIterator 对象可以通过调用列表接口中的 listIterator() 方法来创建。
// Here "l" is any list object. ltr is of
// type ListIterator interface and refers to "l"
ListIterator ltr = l.listIterator();
Java
// A Java program to demonstrates the
// difference between Enumeration,
// Iterator, and ListIterator
import java.io.*;
import java.util.*;
class GFG {
public static void main(String args[])
{
// Creating a vector object
Vector v = new Vector();
// Adding elements to the vector object
v.add(10);
v.add(20);
v.add(30);
v.add(40);
v.add(50);
System.out.println("Enumeration: ");
// Creating an Enumeration object
Enumeration e = v.elements();
// Checking the next element availability
while (e.hasMoreElements()) {
// Moving cursor to the next element
int i = (Integer)e.nextElement();
// Printing the element
System.out.print(i + " ");
}
System.out.println();
System.out.println();
System.out.println("Iterator: ");
// Creating Iterator object
Iterator itr = v.iterator();
// Checking the next element availability
while (itr.hasNext()) {
// Moving cursor to the next element
int i = (Integer)itr.next();
// Checking if i == 10 then
// remove the element
if (i == 10)
itr.remove();
}
System.out.println(v);
System.out.println();
System.out.println("ListIterator: ");
// Creating ListIterator object
ListIterator ltr = v.listIterator();
// Checking the next element availability
while (ltr.hasNext()) {
// Moving cursor to the next element
int i = (Integer)ltr.next();
// Performing add, remove, and
// replace operation
if (i == 20)
ltr.remove();
else if (i == 30)
ltr.add(60);
else if (i == 40)
ltr.set(100);
}
System.out.println(v);
}
} 输出
Enumeration:
10 20 30 40 50
Iterator:
[20, 30, 40, 50]
ListIterator:
[30, 60, 100, 50]
表示出枚举，迭代器，和的ListIterator之间的区别
| Property | Enumeration | Iterator | ListIterator |
| 1. Where we can apply? | It can be applied only to the legacy classes. | It can be applied to any collection interface. | It can be applied to the only list interface. |
| 2. Is it a legacy? | Yes (introduced in 1.0 V). | No (introduced in 1.2 V). | No (introduced in 1.2 V). |
| 3. Allowed Movement | Single direction, i.e we can traverse elements present in the collection only in the forward direction. | Single direction, i.e we can traverse elements present in the collection only in the forward direction. | Bidirectional, i.e we can traverse elements present in the collection both in forward and backward directions. |
| 4. Allowed Operation | We can only perform the read operation. | We can perform read and remove operation. | We can perform read, remove, add, and replace operations. |
| 5. How can we get it? | By calling elements() method present in the vector class. | By calling iterator() method present in any collection interface. | By calling listIterator() method present in the list interface. |