Synchronization we have discussed in detail on java multithreading interview questions and answers.
Since ArrayList is non-synchronized and should not be used in multithreaded environment without explicit synchronization.In this tutorial we will learn about how to synchronize ArrayList in java.
Method 1 : Using Collections.synchronizedList()
One liner is using Collections.synchronizedList() we can make ArrayList synchronized.
import java.util.*;
public class SynchronizedArrayList {
public static void main(String args[]) {
// Converting ArrayList to Synchronized ArrayList
ListString> synchronizedarraylist =
Collections.synchronizedList(new ArrayListString>());
//Adding elements to synchronized ArrayList
synchronizedarraylist.add("Basketball");
synchronizedarraylist.add("Baseball");
synchronizedarraylist.add("Football");
System.out.println("Synchronized ArrayList Iteration:");
synchronized(synchronizedarraylist) {
IteratorString> iterator = synchronizedarraylist.iterator();
while (iterator.hasNext())
System.out.println(iterator.next());
}
}
}
Output
Synchronized ArrayList Iteration:
Basketball
Baseball
Football
Method 2 :Using CopyOnWriteArrayList
import java.util.*;
import java.util.concurrent.*;
public class SynchronizedArrayList {
public static void main(String args[]) {
// Creating Synchronized ArrayList Object
CopyOnWriteArrayListString> al = new CopyOnWriteArrayListString>();
//Adding elements to synchronized ArrayList
al.add("Basketball");
al.add("Baseball");
al.add("Football");
System.out.println("Showing synchronized ArrayList Elements:");
//Synchronized block is not required in this method
IteratorString> iterator = al.iterator();
while (iterator.hasNext())
System.out.println(iterator.next());
}
}
Output
Showing synchronized ArrayList Elements:
Basketball
Baseball
Football
