CopyOnWriteArrayList and CopyOnWriteArraySet

 Fundamentals of CopyOnWriteArrayList and CopyOnWriteArraySet

[1.] The basic thing behind the CopyOnWriteArrayList and CopyOnWriteArraySet is all mutable operations make a copy of the backing array first, make the change to the copy, and then replace the copy.

[2]. If we want to share the data structure among several threads where we have few writes and many reads then we can use CopyOnWriteArrayList and CopyOnWriteArraySet.

[3]. The CopyOnWrite... collections avoid ConcurrentModificationException issues during traversal by traversing through the original collection and the modifications happening in a copy of the original store.

[4]. CopyOnWriteArrayList is a thread-safe version of ArrayList without the syncrhonized access limitations. Both are available in java.util.concurrent package.
 

//Sample example of CopyOnWriteArrayList  which is used to avoid ConcurrentModificationException and  UnsupportedOperationException
package com.corejava.gaurav.examples;

import java.util.Iterator;
import java.util.ListIterator;
import java.util.concurrent.CopyOnWriteArrayList;


public class CopyOnWriteArrayListTestExample {

    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static void main(String args[]){
        CopyOnWriteArrayList clst = new CopyOnWriteArrayList();
        clst.add("Shivam");
        clst.add("Priyanka");
        ListIterator itr = clst.listIterator();
        while(itr.hasNext()){
            System.out.println("Elements are->"+itr.next());
            clst.add("Dhanush");
       
        }
        Iterator itr1 = clst.iterator();
        while(itr1.hasNext()){
            System.out.println("after Modification Elements are->"+itr1.next());
        }
    }
}


//Sample example of CopyOnWriteArraySet  which is used to avoid ConcurrentModificationException and  UnsupportedOperationException

package com.corejava.gaurav.examples;
import java.util.Iterator;
import java.util.concurrent.CopyOnWriteArraySet;


public class CopyOnWriteArraySetTestExample {
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static void main(String args[]){
        CopyOnWriteArraySet cset = new CopyOnWriteArraySet();
        cset.add("Mitali");
        cset.add("Nikhil");
       
        Iterator itr = cset.iterator();
       
        while(itr.hasNext()){
            System.out.println("Set Elements are-"+itr.next());
            cset.add("Vishal");
        }
       
        Iterator itr1 = cset.iterator();
       
        while(itr1.hasNext()){
            System.out.println("After Modification Set Elements are-"+itr1.next());
           
        }
    }
}