php editor Zimo will provide you with a detailed analysis of Java thread synchronization and mutual exclusion to help you navigate the concurrent world with ease. In today's era of information explosion, multi-thread programming has become an essential skill. Understanding how to achieve thread synchronization and mutual exclusion is crucial to improving program performance. Through this article, you will learn how to use the keywords synchronized, Lock interface, and volatile keywords in Java to achieve thread synchronization and mutual exclusion, making your program more stable and efficient in a concurrent environment.

Java provides rich thread synchronization and mutual exclusion mechanisms to help developers solve the challenges in concurrent programming. These mechanisms mainly include locks, atomic operations and volatile keywords. Locks are used to protect shared resources. They allow one thread to monopolize the resource when accessing it, preventing other threads from accessing it at the same time, thereby avoiding data inconsistency and program crashes. An atomic operation refers to an uninterruptible operation, which ensures that while a thread performs an atomic operation, other threads cannot access the shared variables involved in the operation. The volatile keyword can modify a variable to make it visible between multiple threads and prohibit the compiler from optimizing the variable.

In order to better understand the Java thread synchronization and mutual exclusion mechanism, let us demonstrate the usage of these mechanisms through code examples. First, we create a shared resource class that contains a variable count for counting:

public class SharedResource {
private int count = 0;

public synchronized void increment() {
count++;
}

public synchronized int getCount() {
return count;
}
}

In the SharedResource class, we use the synchronized keyword to modify the increment() method and getCount() method, which means that these two methods are synchronized methods. When one thread executes the synchronized method, other threads will be blocked. , until the first thread completes execution. This ensures that the count variable is safe across multiple threads.

Next, we create a thread class to simulate concurrent access to shared resources:

public class MyThread extends Thread {
private SharedResource sharedResource;

public MyThread(SharedResource sharedResource) {
this.sharedResource = sharedResource;
}

@Override
public void run() {
for (int i = 0; i < 10000; i++) {
sharedResource.increment();
}
}
}

In the MyThread class, we use the SharedResource object as a parameter, and increase the count variable concurrently by calling the increment() method in the run() method.

Finally, we create a main class to create multiple threads and start them:

public class Main {
public static void main(String[] args) {
SharedResource sharedResource = new SharedResource();

MyThread[] threads = new MyThread[10];
for (int i = 0; i < 10; i++) {
threads[i] = new MyThread(sharedResource);
threads[i].start();
}

for (MyThread thread : threads) {
try {
thread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}

System.out.println("Final count: " + sharedResource.getCount());
}
}

In the main class, we created a SharedResource object and created 10 MyThread objects, each using the same SharedResource object. Then, we start these 10 threads and wait for them all to finish executing. Finally, we output the value of the count variable and verify that its final value is 100000, which shows that the thread synchronization mechanism effectively guarantees the correctness of the count variable.

Through the above example, we demonstrate how to use Java thread synchronization and mutual exclusion mechanisms to protect shared resources. In actual development, developers need to choose an appropriate synchronization mechanism based on specific needs to ensure the correctness and reliability of concurrent programs.

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