What is the difference between synchronized and concurrent in Java?

What is the difference between synchronized and concurrent in Java?

I'd be happy to help!

In Java, synchronized and concurrent are two key concepts that relate to multithreading and concurrency. While they're often used together, they serve different purposes.

Synchronized

The synchronized keyword is used to ensure that only one thread can execute a particular block of code at any given time. This is achieved by acquiring a lock (known as a monitor) on an object before executing the code. The lock ensures that other threads attempting to enter the same block of code will be blocked until the first thread has finished.

Here are some key characteristics of synchronized:

Example:

public class SynchronizedExample {
public void someMethod() {
synchronized (this) {
// This code can only be executed by one thread at a time.
}
}
}

Concurrent

The concurrent concept refers to the ability of multiple threads to execute simultaneously, without interfering with each other. Concurrency is about handling a large number of tasks in parallel, where each task might have its own set of dependencies and requirements.

Here are some key characteristics of concurrency:

Example:

public class ConcurrentExample {
public void someMethod() {
ExecutorService executor = Executors.newFixedThreadPool(5);
for (int i = 0; i < 10; i++) {
final int taskNumber = i;
Runnable task = () -> System.out.println("Task " + taskNumber + " executed");
executor.submit(task);
}
}
}

Key differences

In summary, synchronized is about exclusive access to shared resources, while concurrency is about handling multiple tasks in parallel without interference. While they're related, these two concepts serve different purposes in Java multithreading and concurrency programming.

java synchronized object

I understand that you want me to respond in English only, so I'll explain the concept of synchronized objects in Java.

In Java, when multiple threads attempt to access shared resources simultaneously, it's essential to ensure data consistency and integrity. This is where synchronization comes into play. The synchronized keyword is used to synchronize access to a block of code or an object, ensuring that only one thread can execute that code at a time.

A synchronized object is one that has been marked as requiring exclusive access by multiple threads. When multiple threads try to access a synchronized object, Java uses a mechanism called the "monitor" to manage access. The monitor is essentially a lock that controls access to the object. Here's how it works:

Here's an example of using synchronized with objects in Java:

public class BankAccount {
private int balance;
public BankAccount(int initialBalance) {
this.balance = initialBalance;
}
public synchronized void deposit(int amount) {
balance += amount;
}
public synchronized void withdraw(int amount) {
if (balance >= amount) {
balance -= amount;
} else {
throw new InsufficientFundsException();
}
}
public int getBalance() {
return balance;
}
}

In this example, the BankAccount class has two synchronized methods: deposit and withdraw. These methods ensure that only one thread can modify the account's balance at a time. This is crucial for maintaining data consistency in a multi-threaded environment.

When using synchronized objects, it's essential to consider the implications on performance and concurrency. Synchronization can introduce overhead and slow down your program, especially if you're dealing with highly concurrent systems. In such cases, you might need to use more sophisticated synchronization mechanisms or alternative concurrency control strategies.

In summary, Java's synchronized keyword provides a mechanism for controlling access to shared resources in multi-threaded environments. By ensuring exclusive access to objects, it helps maintain data consistency and integrity, preventing unexpected behavior and potential bugs.