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

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

iterator returned by CopyOnWriteArrayList is fail-safe. Means any structural modification made to CopyOnWriteArrayList like adding or removing elements during Iteration won’t throw any Exception.

import java.util.Collections;

import java.util.Enumeration;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListTest {

public static void main(String args[]) {

List<String> copyOnWriteArrayList = new CopyOnWriteArrayList<String>();

copyOnWriteArrayList.add("ind");

copyOnWriteArrayList.add("america");

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

// fail-safe

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

while (iterator.hasNext()) {

copyOnWriteArrayList.add("newEle1");

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

}

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

// fail-safe

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

while (listIterator.hasNext()) {

copyOnWriteArrayList.add("newEle2");

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

}

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

// fail-safe

Enumeration<String> listEnum = Collections

.enumeration(copyOnWriteArrayList);

while (listEnum.hasMoreElements()) {

copyOnWriteArrayList.add("newEle3");

System.out.println(listEnum.nextElement());

}

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

// fail-safe

for (String string : copyOnWriteArrayList) {

copyOnWriteArrayList.add("newEle");

System.out.println(string);

}

/*OUTPUT

-------use iterator-------

ind

america

-------use listIterator-------

ind

america

newEle1

-------use Enumeration-------

ind

america

newEle1

newEle2

-------use enhanced for loop-------

ind

america

newEle1

newEle2

newEle3

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Labels: Collection programs Core Java