A detailed explanation of Java multithreading

1 year ago
Jackson Davis
2 minutes

Java multi-threading refers to the mechanism of simultaneously executing multiple threads in a program. There are two ways to implement Java multi-threading: extending the Thread class and implementing the Runnable interface.

Inheriting from the Thread class:

  1. Create a subclass that inherits from the Thread class.
  2. Override the run() method in the subclass to define the code that the thread should execute.
  3. Create an instance of a subclass and invoke the start() method to initiate the thread.

Here is an example code:

class MyThread extends Thread{
    public void run(){
        // 线程要执行的代码
    }
}

public class Main{
    public static void main(String[] args){
        MyThread t1 = new MyThread();
        t1.start();
    }
}

The way to implement the Runnable interface:

  1. Create a class that implements the Runnable interface.
  2. Implement the run() method of the Runnable interface to define the code that the thread should execute.
  3. Create an instance of the Runnable interface and pass it to the constructor of the Thread class.
  4. Start the thread by calling the start() method of the Thread class.

The sample code is shown below:

class MyRunnable implements Runnable{
    public void run(){
        // 线程要执行的代码
    }
}

public class Main{
    public static void main(String[] args){
        MyRunnable runnable = new MyRunnable();
        Thread t1 = new Thread(runnable);
        t1.start();
    }
}

Characteristics of Java multithreading:

  1. Threads are independent units of execution, each with its own stack space.
  2. Threads can share data between each other, but it is important to note the issues of thread safety.
  3. The order of thread execution is unpredictable, determined by the system scheduler.

It should be noted that in multi-threaded programming, thread safety should be taken into consideration. For example, multiple threads simultaneously modifying the same variable can cause data inconsistency issues. One solution is to use the synchronized keyword to lock critical code blocks, ensuring that only one thread can access the block at a time.

Additionally, Java offers a variety of classes and methods related to threads. For example, the sleep() method in the Thread class can make a thread sleep for a period of time, and the join() method in the Thread class can wait for other threads to finish before continuing execution. These methods can assist in the implementation of multi-threaded programming.

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