In Java, a thread is a lightweight subprocess, which means that multiple threads can run concurrently within a single process. The Thread class is a fundamental class that represents a thread of execution. It provides several methods for creating, starting, and controlling a thread.
In this article, we will cover the basics of the Thread class in Java, including creating threads, synchronizing threads, and handling thread exceptions.
Creating Threads
To create a new thread, you can either extend the Thread class and override its run() method or implement the Runnable interface and pass an instance of the class to a Thread constructor.
Here is an example of extending the Thread class:
public class MyThread extends Thread {
public void run() {
// code to be executed in this thread
}
}
And here is an example of implementing the Runnable interface:
public class MyRunnable implements Runnable {
public void run() {
// code to be executed in this thread
}
}
// Creating a new thread from MyRunnable
MyRunnable runnable = new MyRunnable();
Thread thread = new Thread(runnable);
Once you have created a thread, you can start it by calling its start() method. This will cause the run() method to be executed in a separate thread.
thread.start();
Synchronizing Threads
When multiple threads access shared data, it is important to ensure that they do not interfere with each other. This can be achieved through synchronization, which involves using locks to ensure that only one thread can access a shared resource at a time.
In Java, synchronization is achieved through the use of the synchronized keyword. You can use it to synchronize a method or a block of code.
Here is an example of synchronizing a method:
public synchronized void doSomething() {
// code to be executed in this method
}
This will ensure that only one thread can execute the doSomething() method at a time.
You can also synchronize a block of code using the synchronized keyword:
synchronized (obj) {
// code to be executed in this block
}
Here, obj is an object that will be used as a lock. Only one thread can hold the lock at a time, so this will ensure that the code in the block is executed atomically.
Handling Thread Exceptions
When a thread encounters an exception, it will terminate unless the exception is caught and handled. You can catch exceptions in a thread using a try-catch block.
Here is an example of catching an exception in a thread:
public void run() {
try {
// code that might throw an exception
} catch (Exception e) {
// handle the exception
}
}
It is important to handle exceptions in threads, as unhandled exceptions can cause a thread to terminate abruptly, potentially leaving the system in an inconsistent state.
Conclusion
The Thread class in Java is a fundamental class that provides several methods for creating, starting, and controlling a thread. By understanding how to create threads, synchronize threads, and handle thread exceptions, you can write multithreaded applications that are efficient and reliable.
