How to implement JAVA core multi-threaded programming skills

As an excellent programming language, Java is widely used in enterprise-level development. Among them, multi-threaded programming is one of the core contents of Java. In this article, we will introduce how to use Java's multi-threaded programming techniques, as well as specific code examples.

1. How to create a thread

There are two ways to create a thread in Java, namely inheriting the Thread class and implementing the Runnable interface.

The way to inherit the Thread class is as follows:

public class ExampleThread extends Thread {
    public void run() {
        //线程执行的代码
    }
}

The way to implement the Runnable interface is as follows:

public class ExampleRunnable implements Runnable {
    public void run() {
        //线程执行的代码
    }
}

It should be noted that the way to implement the Runnable interface is more recommended. Because Java classes can only be inherited individually, if you inherit the Thread class, you cannot inherit other classes. Moreover, implementing the Runnable interface is more in line with object-oriented thinking, which is to separate threads from their specific tasks and reduce the coupling between classes.

2. The use of synchronization and locks

In multi-thread programming, since multiple threads are executed concurrently, if no processing is done, data inconsistency may occur. Condition. To this end, Java provides synchronization and lock mechanisms to control access between multiple threads.

The synchronization mechanism can be added to methods or code blocks, as follows:

public synchronized void method(){
    //线程要执行的代码
}

public void run() {
    synchronized(this) {
        //线程要执行的代码
    }
}

The function of the synchronization mechanism is to ensure that only one thread can access the synchronized code block or method at the same time. This avoids data races and data inconsistencies.

The use of locks can achieve more powerful control, as follows:

Lock lock = new ReentrantLock();
public void method(){
    lock.lock();
    try{
        //线程要执行的代码
    }finally{
        lock.unlock();
    }
}

The function of locks is the same as the synchronization mechanism, but locks can also achieve more complex control. For example, you can apply for a lock through the lock() method, and release the lock through the unlock() method. You can also try to apply for a lock through the tryLock() method, wait for a period of time, and then give up the application if it is not applied for.

3. Use of thread pool

The thread pool is a common component of multi-threaded programming in Java. When creating threads, if threads are frequently created and destroyed, it will cause a waste of system resources and degrade performance. The thread pool can reuse already created threads to improve thread utilization and system performance.

The thread pool is created and used as follows:

ExecutorService threadPool = Executors.newFixedThreadPool(10);
for(int i=0;i<100;i++){
    threadPool.execute(new Runnable(){
        public void run(){
            //线程执行的代码
        }
    });
}

In the above code, we use the thread pool to execute 100 tasks. Among them, the newFixedThreadPool(10) method creates a thread pool with a fixed size of 10, and the execute() method is used to submit tasks to the thread pool.

The advantage of the thread pool is that you can control the resource utilization of the system by setting the size of the thread pool, and can reduce the overhead of thread creation and destruction. In addition, the thread pool can also handle issues such as exceptions and task cancellation, with better maintainability and reliability.

Summary

Java's multi-threaded programming skills involve thread creation, synchronization and locks, thread pools and many other aspects. At any time, multi-threading design must take into account data consistency and high reliability. Therefore, we need to master Java's core multi-threaded programming skills in order to write high-quality concurrent programs.

In this article, we introduce the creation method of threads in Java, the use of synchronization and locks, and the application of thread pools. Hope this helps.

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