---
title: "Discuss the volatile keyword in Java and its role in concurrency."  
description: "Volatile keyword is used to indicate that a variable's value may be modified by multiple threads concurrently."  
author: "Ashutosh Patel"  
published: 2024-07-23  
updated: 2024-07-23  
canonical: https://www.mindstick.com/blog/304522/discuss-the-volatile-keyword-in-java-and-its-role-in-concurrency  
category: "java"  
tags: ["java", "concurrent programming", "keywords"]  
reading_time: 3 minutes  

---

# Discuss the volatile keyword in Java and its role in concurrency.

The `volatile` keyword is used to indicate that the value of a variable can be changed simultaneously with multiple formulas. It simultaneously plays an important role by promising shared change to ensure `visibility`. Here are the main parts and their [implications](https://yourviews.mindstick.com/view/87391/balancing-act-the-implications-of-west-bengal-s-investment-in-madrasas) in using volatile.

#### Visibility Guarantee

If a [variable is declared](https://www.mindstick.com/interview/23061/how-variable-is-declared-in-php) `volatile`, any read and write [operations](https://www.mindstick.com/blog/304985/how-does-devops-bridge-the-gap-between-development-and-operations-teams-like-git) on that variable are atomic. This means that changes made by one thread to a `volatile` variable are immediately recognized by another thread. Without flexibility, threads can cache changes or optimize their reads and writes so that changes introduced by one thread are not immediately [visible to others](https://answers.mindstick.com/qa/115848/why-are-my-quora-answers-not-visible-to-others)

#### No Atomicity or Compound Actions

It is important to note that the `volatile` does not cause atomization for compound reactions. For example, incrementing a `volatile` variable (`count++`) is not atomic because it involves a read-modify-write operation, which can be canceled by other threads

#### Memory Ordering

Using `volatile` also ensures that read and write operations on a variable are not reconfigured by the compiler or CPU. This is especially important in multiprocessor systems where threads can operate on different CPUs with their own cache. If it is not confusing, a formula can read an outdated value from its cache, resulting in incorrect behavior.

#### Use Cases for `volatile`

**Flag Variables-** `volatile` is often used for Boolean flags that control the operation between threads.

```java
public class SharedResource {
   private volatile boolean flag = false;
   public void setFlag() {
       flag = true;
   }
   public boolean isFlagSet() {
       return flag;
   }
}
```

In this example, the `flag` is marked as `volatile` to ensure that a change made by one thread (setting the flag to `true`) is immediately recognized by other threads.

**Status Flags in Thread [Coordination](https://answers.mindstick.com/qa/72258/who-was-launching-a-new-scheme-indian-cyber-crime-coordination-centre-i4c-to-combat-cybercrime-in-the-country)**

This is useful to identify between threads where one thread sets the flag and another checks it.

```java
public class Worker extends Thread {
   private volatile boolean running = true;
   @Override
   public void run() {
       while (running) {
           // do work
       }
   }
   public void stopWorker() {
       running = false;
   }
}
```

Here the `running` flag is used to control the loop in the `Worker` thread. Setting `running` to `false` in `stopWorker()` will stop the thread immediately due to the visibility promised by `volatile`.

#### When Not to Use `volatile`

**Mutual Exclusion-** `volatile` does not provide mutual exclusion, so it is not suitable for cases where variables shared by multiple threads need to be updated atomically.

**Performance Considerations-** Although `volatile` ensures visibility and configurability guarantees, overuse of `volatility` can affect performance due to frequent cache invalidations between threads

\
The `volatile` keyword in Java ensures that changes to a variable made by one thread are immediately recognized by another thread. To ensure proper [thread safety](https://www.mindstick.com/forum/159021/what-are-rust-s-mechanisms-for-ensuring-thread-safety-in-concurrent-programming) and [synchronization](https://www.mindstick.com/articles/11983/synchronization-in-c-sharp) in [concurrent programming](https://www.mindstick.com/articles/12001/concurrent-programming-in-erlang), especially for flag variables and simple status pointers in threads it is important to understand its uses and [limitations](https://www.mindstick.com/interview/121/what-are-the-benefits-and-limitations-of-using-hidden-fields) and it is important to create proper and efficient concurrent Java applications.

**Also, Read:** [Differentiate between checked and unchecked exceptions in Java with examples.](https://www.mindstick.com/blog/304521/differentiate-between-checked-and-unchecked-exceptions-in-java-with-examples)

---

Original Source: https://www.mindstick.com/blog/304522/discuss-the-volatile-keyword-in-java-and-its-role-in-concurrency

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