Atomic vs volatile vs synchronized Java

Atomic vs volatile vs synchronized Java

I'll respond in English only.

In Java, atomic, volatile, and synchronized are three keywords used to achieve thread safety. Each has its own unique properties and uses.

Atomic

The atomic keyword is not actually a keyword in Java, but rather a class from the java.util.concurrent.atomic package. Atomic variables are designed to be updated by multiple threads without using locks. They provide a way to safely update variables that are accessed concurrently by multiple threads.

Atomic variables can be used to implement thread-safe counters, flags, and other variables that need to be updated atomically. The atomic operations provided by the Atomic class include get(), set(), compareAndSet(), incrementAndGet(), etc.

Here's an example of how you might use AtomicInteger:

AtomicInteger count = new AtomicInteger(0);
while (true) {
int currentValue = count.get();
if (currentValue > 100) {
break;
}
count.incrementAndGet();
}

Volatile

The volatile keyword is a keyword in Java that can be used to make variables thread-safe. A volatile variable is not guaranteed to have its value updated immediately, but changes made by one thread are always visible to other threads.

In other words, when a field is declared as volatile, the JVM will reload its value from main memory whenever it's accessed or updated. This ensures that all threads see the latest value of the variable.

Here's an example:

class Counter {
private volatile int count = 0;
public void increment() {
count++;
}
public int getCount() {
return count;
}
}

In this example, even though multiple threads are accessing and updating the count variable, they will always see the latest value.

Synchronized

The synchronized keyword is a keyword in Java that can be used to make methods or blocks of code thread-safe. When a method is declared as synchronized, only one thread can execute it at a time.

Here's an example:

class Printer {
private Object lock = new Object();
public void print(String message) {
synchronized (lock) {
System.out.println(message);
}
}
}

In this example, only one thread can print a message at a time. This ensures that the printer is not accessed concurrently.

In summary:

Each has its own unique properties and uses, but they all help ensure thread safety in Java.

What is transient and volatile in Java?

I'm happy to help you with that!

In Java, "transient" and "volatile" are two keyword attributes used to manipulate the behavior of object fields.

Transient:

A transient field is a non-serializable field, meaning it will not be included in the serialization process. Serialization is the process of converting an object's state into a byte stream that can be written to a file or transmitted over a network. When you declare a field as transient, you're essentially telling Java that this field should not be serialized.

Here are some scenarios where using transient makes sense:

Volatile:

A volatile field is a special type of field that is used for shared access to variables in multithreaded environments. When you declare a field as volatile, Java ensures that any changes made to the field are immediately visible to all threads that access it, even if they're running concurrently.

Here are some use cases for volatile:

In summary, transient is used to exclude fields from serialization, while volatile is used to ensure thread-safety and visibility for shared variables in multithreaded environments. Both keywords play important roles in Java programming, particularly when dealing with complex object interactions and concurrent access scenarios.