Multithreading Interview Questions

Multithreading in Java refers to concurrent execution of two or more threads. Java supports multithreading through the `Thread` class and `Runnable` interface, allowing multiple threads to run concurrently, improving performance for tasks like network operations, database queries, etc.

A thread in Java is a lightweight process. Each thread has its own call stack, and multiple threads can exist within the same program. Threads can be created by extending the `Thread` class or implementing the `Runnable` interface.

A `synchronized` method locks the entire method for a thread, ensuring only one thread can execute it at a time. A `synchronized` block locks only a specific block of code, providing a finer level of control over thread synchronization.

The `volatile` keyword in Java indicates that a variable's value will be modified by different threads. It ensures visibility and ordering of changes made to the variable across threads, preventing caching of variable values by threads.

A deadlock in Java occurs when two or more threads are blocked forever, waiting for each other to release resources. Deadlocks occur when threads acquire locks in different orders. Avoiding deadlocks requires careful design of locking mechanisms.