Why is immutability considered a beneficial property in multi-threaded applications?

Immutability is a valuable property in multi-threaded applications because an immutable object's state cannot change after it is created. Since the data remains constant, multiple threads can safely access and share the same object without requiring synchronization, reducing complexity and improving application reliability.

Key Points: • Immutable objects are inherently thread-safe because their state cannot be modified after creation. • They eliminate race conditions and data inconsistency issues caused by concurrent updates. • Reduced synchronization requirements often lead to simpler code, better scalability, and improved performance.

Example: The String class is immutable. Multiple threads can safely read and share the same String instance without worrying about one thread modifying its value and affecting others.

Code Example:

public final class Employee {

    private final int id;
    private final String name;

    public Employee(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

public class Main {

    public static void main(String[] args) {

        Employee employee =
                new Employee(101, "John");

        System.out.println(
                employee.getName());
    }
}

Interview Tip: A concise interview answer is: Immutability is beneficial in multi-threaded applications because immutable objects cannot be modified after creation. This makes them inherently thread-safe, eliminates race conditions, reduces the need for synchronization, and simplifies concurrent programming while improving reliability and performance.