javalangThreadinterrupt

In Java, `Thread` is a fundamental class in the `java.lang` package that represents a thread of execution within a program. Threads allow concurrent execution, enabling multiple tasks to run simultaneously, which can improve performance in CPU-bound or I/O-bound applications. The `Thread` class extends the `Object` class and implements the `Runnable` interface, providing methods for thread lifecycle management, synchronization, and inter-thread communication.

A thread is created by either extending the `Thread` class or implementing the `Runnable` interface. When a thread is started via the `start()` method, it begins execution in a separate path of control, running independently of the main thread. The `run()` method contains the code that the thread will execute. Threads can be prioritized using the `setPriority()` method, though priority does not guarantee execution order.

Key lifecycle states of a thread include:

- **New**: Created but not yet started.

- **Runnable**: Ready to run, waiting for CPU time.

- **Running**: Executing the `run()` method.

- **Blocked/Waiting**: Temporarily paused due to I/O, synchronization, or explicit waiting.

- **Terminated**: Execution has completed or an unhandled exception occurred.

Thread synchronization is managed using `synchronized` blocks or methods, ensuring that only one thread accesses a shared resource at a time to prevent race conditions. The `wait()`, `notify()`, and `notifyAll()` methods facilitate communication between threads, allowing them to coordinate execution.

Common thread-related exceptions include `InterruptedException`, thrown when a thread is interrupted while waiting or sleeping, and `ThreadDeath`, which terminates a thread abruptly. Proper resource cleanup and exception handling are essential to avoid memory leaks or deadlocks.

Threads are widely used in Java for multitasking, but excessive threading can lead to overhead. Modern alternatives like the `java.util.concurrent` package (e.g., `ExecutorService`, `ForkJoinPool`) provide higher-level abstractions for managing thread pools and task scheduling.