The CopyOnWriteArraySet.contains()
method in Java is used to check if a CopyOnWriteArraySet
contains a specified element.
Table of Contents
- Introduction
contains
Method Syntax- Examples
- Checking if an Element Exists
- Handling Non-Existent Elements
- Real-World Use Case
- Example: Checking User Presence in a Thread-Safe Set
- Conclusion
Introduction
The CopyOnWriteArraySet
is a thread-safe variant of Set
in Java. It is part of the java.util.concurrent
package and is designed for scenarios where read operations are more frequent than write operations. The contains
method allows you to check if the set contains a specified element. The CopyOnWriteArraySet
achieves thread safety by creating a new copy of the underlying array whenever it is modified.
contains() Method Syntax
The syntax for the contains
method is as follows:
public boolean contains(Object o)
- The method takes one parameter:
o
of typeObject
, which represents the element whose presence in the set is to be tested.
- The method returns
true
if the set contains the specified element, andfalse
otherwise.
Examples
Checking if an Element Exists
The contains
method can be used to check if a CopyOnWriteArraySet
contains a specified element.
Example
import java.util.concurrent.CopyOnWriteArraySet;
public class ContainsExample {
public static void main(String[] args) {
// Creating a CopyOnWriteArraySet with String elements
CopyOnWriteArraySet<String> names = new CopyOnWriteArraySet<>();
// Adding elements to the CopyOnWriteArraySet
names.add("Ravi");
names.add("Priya");
names.add("Vijay");
// Checking if the set contains an element
boolean containsPriya = names.contains("Priya");
// Printing the result
System.out.println("Does the set contain 'Priya'? " + containsPriya);
}
}
Output:
Does the set contain 'Priya'? true
Handling Non-Existent Elements
The contains
method returns false
if the specified element is not found in the CopyOnWriteArraySet
.
Example
import java.util.concurrent.CopyOnWriteArraySet;
public class NonExistentElementExample {
public static void main(String[] args) {
// Creating a CopyOnWriteArraySet with String elements
CopyOnWriteArraySet<String> names = new CopyOnWriteArraySet<>();
// Adding elements to the CopyOnWriteArraySet
names.add("Ravi");
names.add("Priya");
names.add("Vijay");
// Checking if the set contains a non-existent element
boolean containsAnita = names.contains("Anita");
// Printing the result
System.out.println("Does the set contain 'Anita'? " + containsAnita);
}
}
Output:
Does the set contain 'Anita'? false
Real-World Use Case
Example: Checking User Presence in a Thread-Safe Set
A common real-world use case for CopyOnWriteArraySet
is managing a thread-safe set of users and checking if a specific user is present in the set.
Example
import java.util.concurrent.CopyOnWriteArraySet;
public class UserSetManager {
public static void main(String[] args) {
// Creating a CopyOnWriteArraySet to manage user names
CopyOnWriteArraySet<String> userSet = new CopyOnWriteArraySet<>();
// Adding user names to the CopyOnWriteArraySet
userSet.add("Ravi");
userSet.add("Priya");
userSet.add("Vijay");
// Simulating concurrent operations
Thread checkUserThread1 = new Thread(() -> {
boolean containsPriya = userSet.contains("Priya");
System.out.println("Does the set contain 'Priya'? " + containsPriya);
});
Thread checkUserThread2 = new Thread(() -> {
boolean containsAnita = userSet.contains("Anita");
System.out.println("Does the set contain 'Anita'? " + containsAnita);
});
// Starting the threads
checkUserThread1.start();
checkUserThread2.start();
// Waiting for the threads to finish
try {
checkUserThread1.join();
checkUserThread2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
// Printing the final user set
System.out.println("Final user set: " + userSet);
}
}
Output:
Does the set contain 'Priya'? true
Does the set contain 'Anita'? false
Final user set: [Ravi, Priya, Vijay]
In this example, CopyOnWriteArraySet
is used to manage a thread-safe set of user names, allowing concurrent operations while checking for the presence of specific users.
Conclusion
The CopyOnWriteArraySet.contains()
method in Java provides a way to check if a CopyOnWriteArraySet
contains a specified element in a thread-safe manner. By understanding how to use this method, you can efficiently manage collections of elements in your Java applications, especially in concurrent environments. The method allows you to verify the presence of elements, making it a versatile tool for data management in multi-threaded scenarios.