How to develop a multi-threaded application using Java

How to use Java to develop a multi-threaded application

In today's era of rapid development of information technology, multi-threaded programming has become one of the essential skills for developers. one. Using multi-threading can give full play to the performance of the computer and improve the running efficiency of the program. This article will introduce how to use Java to develop a multi-threaded application and provide specific code examples.

Step one: Create a multi-threaded class

In Java, use the Thread class to create and control threads. We need to create a custom class that inherits from the Thread class and implement the specific logic of the thread in this class.

public class MyThread extends Thread {
    @Override
    public void run() {
        // 线程的具体逻辑
    }
}

By inheriting the Thread class, we can override the run() method and write the specific logic of the thread in it. The run() method is the entry point of the thread. When the thread starts, the code in this method will be automatically executed.

Step 2: Start the thread

After creating the custom thread class, we need to start the thread in the main program.

public class Main {
    public static void main(String[] args) {
        MyThread thread = new MyThread();
        thread.start();
    }
}

In the main program, create a MyThread object and call its start() method. The start() method will start this thread so that it can start executing the code in the run() method.

The third step: achieve thread synchronization

Multi-threaded development often needs to consider the synchronization issue between threads. A common problem is multiple threads' access to shared resources. In order to ensure data consistency between threads, we can use the synchronized keyword to achieve thread synchronization.

public class MyThread extends Thread {
    private int count = 0;

    @Override
    public synchronized void run() {
        for (int i = 0; i < 10; i++) {
            count++;
            System.out.println("Thread " + getName() + ": " + count);
        }
    }
}

In the above code, we added the synchronized keyword to the run() method. In this way, when multiple threads access this method at the same time, they will be automatically locked, ensuring mutually exclusive access between threads.

Step 4: Use thread pool

In actual applications, we often need to create multiple threads to process tasks. In order to better manage threads and improve program performance, we can use thread pools to create and manage threads.

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Main {
    public static void main(String[] args) {
        ExecutorService executor = Executors.newFixedThreadPool(5);
        
        for (int i = 0; i < 10; i++) {
            executor.execute(new MyThread());
        }
        
        executor.shutdown();
    }
}

In the above code, we use the ExecutorService interface to create a thread pool. By calling the static method newFixedThreadPool() of the Executors class, you can create a fixed-size thread pool with a number of threads of 5. Then, the task is submitted by calling the execute() method and executed in the thread pool.

Step 5: Communication between threads

In multi-threaded applications, sometimes threads need to communicate, share data or transfer information. Java provides some mechanisms to implement communication between threads.

For example, we can use the wait() and notify() methods to implement the thread's waiting and notification mechanism.

public class MyThread extends Thread {
    private volatile boolean flag = false;
    
    @Override
    public void run() {
        synchronized (this) {
            try {
                while (!flag) {
                    System.out.println("Thread " + getName() + " is waiting");
                    wait();
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        
        System.out.println("Thread " + getName() + " is running");
    }
    
    public void setFlag(boolean flag) {
        this.flag = flag;
    }
}

In the above code, we use the wait() method to put the thread into the waiting state. In the main program, set the flag value to true by calling the setFlag() method, and then call the notify() method to wake up the waiting thread.

Summary:

This article introduces how to use Java to develop a multi-threaded application. Create a custom thread class by inheriting the Thread class, use the synchronized keyword to achieve thread synchronization, use the thread pool to improve program performance, and use the wait() and notify() methods to achieve communication between threads. Multi-threaded development requires careful consideration of thread safety and performance issues. I hope this article can be helpful to readers.

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