JavaMadeSoEasy.com (JMSE): Vector - fail-safe or fail-fast iteration using iterator, listIterator, Enumeration and enhanced for loop

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Vector - fail-safe or fail-fast iteration using iterator, listIterator, Enumeration and enhanced for loop.

iterator returned by Vector is fail-fast. Means any structural modification made to Vector like adding or removing elements during Iteration will throw java.util.ConcurrentModificationException.

Enumeration is fail-safe, means any modification made to Vector during iteration using Enumeration don’t throw any exception.

import java.util.Enumeration;

import java.util.Iterator;

import java.util.ListIterator;

import java.util.Vector;

/**

* Copyright (c), AnkitMittal JavaMadeSoEasy.com

public class VectorTest {

public static void main(String args[]) {

// creates array with initial capacity of 10.

Vector<String> vector = new Vector<String>();

vector.add("ankit");

vector.add("javaMadeSoEasy");

System.out.println("-------use Enumeration-------");

// fail-safe

Enumeration<String> listEnum = vector.elements();

while (listEnum.hasMoreElements()) {

String str = listEnum.nextElement();

if (str.equals("ankit")) {

// adding element will not throw any Exception

vector.add("newEle");

}

System.out.println(str);

}

System.out.println("-------use iterator-------");

// fail-fast

Iterator<String> iterator = vector.iterator();

while (iterator.hasNext()) {

vector.add("newEle"); // unComment to avoid ConcurrentModificationException

System.out.println(iterator.next());

}

System.out.println("-------use listIterator-------");

// fail-fast

ListIterator<String> listIterator = vector.listIterator();

listIterator.next();

listIterator.previous();

while (listIterator.hasNext()) {

vector.add("newEle"); // unComment to avoid ConcurrentModificationException

System.out.println(listIterator.next());

}

System.out.println("-------use enhanced for loop-------");

//enhanced for loop is fail-fast

for (String string : vector) {

vector.add("newEle"); // unComment to avoid ConcurrentModificationException

System.out.println(string);

}

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Labels: Collection programs Core Java