What is the difference between Java synchronously and asynchronously?

In Java, synchronization and asynchronization are terms used to describe the way methods or operations are executed.

Synchronous methods block the current thread when called until the method finishes and returns a result, allowing the next step to continue. The execution order of synchronous methods is determined by the order in which they are called, with each method having to wait for the previous one to finish before it can execute. Synchronous methods are typically used for operations that need to be executed in a specific order, such as multiple threads sequentially reading and modifying shared resources.

Asynchronous methods do not block the current thread when called, instead they immediately return a Future object or handle the method’s result through a callback function. The execution order of asynchronous methods is unpredictable, as each method can run independently without needing to wait for the previous one to finish. Asynchronous methods are commonly used for operations that require concurrent execution, such as multiple threads simultaneously carrying out separate tasks.

In summary, synchronous methods are executed sequentially, requiring the previous method to finish before the next one can be executed; asynchronous methods are executed concurrently, not needing to wait for the previous method to finish before proceeding to the next one.