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

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

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

import java.util.Collections;

import java.util.Enumeration;

import java.util.Iterator;

import java.util.Set;

import java.util.TreeSet;

/** Copyright (c), AnkitMittal JavaMadeSoEasy.com */

public class TreeSetTest {

public static void main(String args[]) {

Set<String> treeSet = new TreeSet<String>();

treeSet.add("ankit");

treeSet.add("javaMadeSoEasy");

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

// fail-fast

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

while (iterator.hasNext()) {

treeSet.add("newElement1"); // unComment to avoid

// ConcurrentModificationException

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

}

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

// fail-fast

Enumeration<String> listEnum = Collections.enumeration(treeSet);

while (listEnum.hasMoreElements()) {

treeSet.add("newElement2"); // unComment to avoid

// ConcurrentModificationException

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

}

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

// enhanced for loop is fail-fast

for (String string : treeSet) {

treeSet.add("newElement3");// unComment to avoid

// ConcurrentModificationException

System.out.println(string);

}