Enumeration and Iterator in Java

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Harjeet Singh

Enumeration and Iterator in Java
4 Answer(s) 5 years and 3 months ago
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Difference between Enumeration and Iterator in Java programming language.

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February 25, 2008 at 12:45 PM

Difference between Enumeration and Iterator

Both are used to go through (traverse) into collection bag.

Enumeration
Enumeration is the part of legacy classes that deals with the objects and it comes with java1.1. Enumeration is used to go through vector, hashtable etc. Enumeration is read only and we can't change the object or value in the collection.we has only forward facility.

Iterator
Iterater is introduced in Collection framework. Iterator is used with loops like while loop, for loop etc. Iterator has an additonal method remove() that allows removal of the item from collection.

Difference between ArrayList and Vector

ArrayList

Arraylist are the new collection and are more flexible than any other collection as arraylists are dynamic in nature. Since the methods of Arraylist are not synchronized therefore they are faster in performace. Arraylist has no default size. In ArrayList data is retrived through get() method.

Vector

Vectors are the old collections therefore they comes under the legacy classes. They are synchronized. Vector has a default size of 10. Vectors are used only in those conditions multiple threads are accessed simultaneously otherwise ArrayList is the best option. Vector grows dynamically. In vector the data is retrieve through elementAt() method.

Difference between Abstract Class and Interface

Abstract Class

An abstract class can contain non-abstract methods. While a class that extends an abstract class need not implement any of the methods defined in the abstract class. The class that extends an abstract class can implement any number of it's own methods. An abstract class can hold the sharable resources. There is no need to make a class fully abstract because in such conditions they impact on performance issues

Interface

In case all the methods are set to be abstract, an interface is used. A class implementing an interface must implement all of the methods defined in the interface, interfaces do not allow to put the sharable resources. We can use an interface as a marker interface.

June 11, 2011 at 2:21 PM

The functionality of Enumeration interface is duplicated by the Iterator interface. Iterator has a remove() method while Enumeration doesn't. Enumeration acts as Read-only interface, because it has the methods only to traverse and fetch the objects, where as using Iterator we can manipulate the objects also like adding and removing the objects. I have also blogged about **Deleted** here.

June 4, 2012 at 11:21 AM

Only major difference between Enumeration and iterator is Iterator has a remove() method while Enumeration doesn't. Enumeration acts as Read-only interface, because it has the methods only to traverse and fetch the objects, where as by using Iterator we can manipulate the objects like adding and removing the objects from collection e.g. Arraylist.

Also Iterator is more secure and safe as compared to Enumeration because it does not allow other thread to modify the collection object while some thread is iterating over it and throws ConcurrentModificationException. This is by far most important fact for me for deciding between Iterator vs Enumeration in Java.

June 4, 2012 at 11:21 AM

Java Enumeration
Java Enumeration In this section you will learn about Enumeration interface... is telling, the Enumeration interface have functions by which you can obtain one element at a time from the collection of object. Now a days, Iterator replaces

Java Enumeration
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Java Iterator with Example
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Collection : Iterator Example
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Java List Iterator
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Iterator Java Tutorial
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Iterator Java Sample
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Java :Thread Enumeration
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Java arraylist iterator
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Iterators
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Example of Hashset iterator method in java.
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Java Generic Iterator
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Java For loop Iterator
Iterator can be used with the for loop also. Initialization of the Iterator is done before the for loop. Iterator has boolean value with the hasNext method. So no increment/decrement is required. Java for Loop Iterator

Java Array Iterator with Example
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Java Hashmap Iterator
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Java Next Iterator
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Java Hashtable Iterator
be traversed by the Iterator. Java Hashtable Iterator Example import... in the key and value form. Like hasmap, it has no iterator() method. Use the entrySet..."); hastab.put("e", "era"); Set s = hastab.entrySet(); Iterator

Java Collection iterator with example
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Java HashMap iterator and example
Java HashMap Iterator is an interface. It keeps the data in the key and value form. It is implemented by HashMap. hashMap doesnot have iterator method... elements can be traversed by the Iterator. Example of Java HashMap

List iterator java example
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How to Define Vector Iterator in Java Program
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Java Set iterator with example
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Iterator Java Order
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Java Map iterator with example
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Java Set Iterator
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Iterator tag example of struts2.2.1
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Vector Iterator Java Example
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Iterator Java Remove
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Java Hasnext Iterator
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Java Vector Iterator
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Iterator Java While
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Iterator Java Size
The Java Iterator size() is the method of the collection Interface... in the collection. Java Size Iterator Example import java.util...." }; for (int i = 0; i < 5; i++) { list.add(country[i]); } Iterator i

Velocity Iterator Tool Example
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Example to show Iterator exception in java
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Java List Iterator Example
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Iterator Java Loop
With iterator all three loops can be used. While, dowhile, and for loop is easy to use with iterator. Example Java Loop Iterator import...(); for (int i = 1; i < 6; i++) { l.add(i); } Iterator

Iterator Java Sort
Sort is a static method of the Collections class. It sorts the contents of the list Collection. Example of Java Sort Iterator import...++) { list.add(country[i]); } Collections.sort(list); Iterator i

J2ME Enumeration Example
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Java Previous Iterator
Java previous Iterator function is present in the listIterator Interface. ListIterator is special iterator for the list. previuos method allows to get... direction. Java Previous Iterate Example import java.util.ArrayList

Iterator Java Reset
iterator interface doesn't have any reset method. In the listIterator the previous method can be used to rsest the list. Example of Java Reset Iterator import java.util.ArrayList; import java.util.Iterator; import

Java nextElement()
() method of interface Enumeration. We are going to use nextElement() method of interface Enumeration in Java. The description of the code is given below... Java nextElement()

Java hasMoreElement()
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Java itrator interface
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Java ArrayList listIterator
listIterator() method is used to return a ListIterator reference of the given list. Using this reference all elements of the list can be iterated. It works similar to the iterator() method. Java Arraylist List Iterator

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