Multithreading in Java

Lecture 93:-  Multithreading in Java

In Java, multithreading is a powerful feature that allows you to create and manage multiple threads of execution within a single Java application. The Java platform provides built-in support for multithreading through the java.lang.Thread class and the java.lang.Runnable interface.

Here's an overview of how multithreading works in Java:

1. Creating Threads:

   • You can create a thread by extending the Thread class and overriding its run() method with the code you want the thread to execute.
   • Alternatively, you can implement the Runnable interface and provide the run() method's implementation. This approach is often preferred because it allows better class design flexibility and supports multiple inheritance.

2. Starting Threads:

   • To start the execution of a thread, you need to call the start() method on the Thread object. The start() method internally calls the run() method, and the thread starts executing its code concurrently with other threads.

3. Thread States:

   • Threads in Java can exist in various states, such as "new," "runnable," "blocked," "waiting," "timed waiting," and "terminated."
   • The Thread class provides methods to transition between these states and control the execution of threads.

4. Thread Synchronization:

   • When multiple threads access shared resources, there is a possibility of data inconsistency and conflicts.
   • Thread synchronization mechanisms, such as synchronized blocks and locks, are used to prevent race conditions and ensure data consistency.

5. Thread Priorities:

   • Threads can be assigned priorities using the setPriority() method, which influences their execution order.
   • Java provides thread priorities ranging from Thread.MIN_PRIORITY to Thread.MAX_PRIORITY, with Thread.NORM_PRIORITY being the default.

6. Thread Joining:

   • The join() method allows one thread to wait for the completion of another thread's execution. This is useful when you want to ensure certain threads finish their tasks before proceeding with the main thread.

7. Thread Pooling:

   • Creating and destroying threads can be resource-intensive. Thread pooling is a technique where a pool of reusable threads is created and maintained, avoiding the overhead of thread creation.

8. Thread Safety:

   • Care must be taken to write thread-safe code to avoid issues like data corruption, race conditions, and deadlocks when multiple threads access shared resources.

Multithreading is beneficial for tasks that involve concurrent processing, such as handling multiple client connections, parallel processing, and handling time-consuming operations without blocking the entire program's execution.

However, multithreading introduces challenges, such as potential data synchronization issues and the need for careful design to avoid race conditions and deadlocks. Therefore, proper understanding of multithreading concepts and good programming practices are essential to create efficient and reliable multithreaded applications in Java.

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