Collections synchronizedCollection() method in Java with Examples

The synchronizedCollection() method of java.util.Collections class is used to return a synchronized (thread-safe) collection backed by the specified collection. In order to guarantee serial access, it is critical that all access to the backing collection is accomplished through the returned collection.
Syntax:

public static <T> Collection<T>
  synchronizedCollection(Collection<T> c)

Parameters: This method takes the collection c as a parameter to be “wrapped” in a synchronized collection.
Return Value: This method returns a synchronized view of the specified collection.
Below are the examples to illustrate the synchronizedCollection() method
Example 1:

Java

// Java program to demonstrate synchronizedCollection()
// method for String Value

import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {

        try {

            // creating object of List<String>
            List<String> vector = new ArrayList<String>();

            // populate the vector
            vector.add("A");
            vector.add("B");
            vector.add("C");
            vector.add("D");
            vector.add("E");

            // printing the Collection
            System.out.println("Collection : " + vector);

            // getting the synchronized view of Collection
            Collection<String> c = Collections
                                       .synchronizedCollection(vector);

            // printing the Collection
            System.out.println("Synchronized view"
                               + " of collection : " + c);
        }

        catch (IndexOutOfBoundsException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output

Collection : [A, B, C, D, E]
Synchronized view of collection : [A, B, C, D, E]

Example 2:

Java

// Java program to demonstrate synchronizedCollection()
// method for Integer Value

import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {

        try {

            // creating object of List<String>
            List<Integer> vector = new ArrayList<Integer>();

            // populate the vector
            vector.add(20);
            vector.add(30);
            vector.add(40);
            vector.add(50);
            vector.add(60);

            // printing the Collection
            System.out.println("Collection : " + vector);

            // getting the synchronized view of Collection
            Collection<Integer> c = Collections
                                        .synchronizedCollection(vector);

            // printing the Collection
            System.out.println("Synchronized view is : " + c);
        }

        catch (IllegalArgumentException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

Collection : [20, 30, 40, 50, 60]
Synchronized view is : [20, 30, 40, 50, 60]