Specific use of multithreading

First, let's take a look at the specific creation of multithreading :

First, there are many ways to create multithreads ->

1. Inherit Thread, rewrite

class MyThread extends Thread{
    @Override
    public void run() {
        
    }
}

public class TextDemo {
    public static void main(String[] args) {
        Thread thread = new MyThread();
    }
}

2. Realization Runnable

class MyRunning implements Runnable{
    @Override
    public void run() {

    }
}

public class TextDemo {
    public static void main(String[] args) {
        MyRunning running = new MyRunning();
        Thread thread = new Thread(running);
        
    }
}

3. Inherit Thread, rewrite run, Use anonymous inner class

public class TextDemo {
    public static void main(String[] args) {
        Thread thread = new Thread(){
            @Override
            public void run() {
                super.run();
            }
        };
    }
}

4. Realization Runable, rewrite run, Use internal expressions

public class TextDemo {
    public static void main(String[] args) {
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                
            }
        });
    }
}

Use lambda expression

public class TextDemo {
    public static void main(String[] args) {
        Thread thread = new Thread(()->{
            System.out.println("hello thread");
        });
        
    }
}

The above is the basic thread creation method .

Thread In fact, the creation and construction methods of are not only added Runnable

In fact, it can also give Thread Add a name to , In order to make the program easy to debug threads

Method	explain
Thread(String name)	Create a thread object and name
Thread(Running target,String name)	Use Running Create objects , And name

 

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Thread Common properties of

ID Is the displacement identifier of the thread , Different counties will not repeat

The name is used by various debugging tools

Status indicates that the ready-made is currently in a situation

Ready made with high priority is theoretically easier to schedule

About background threads , Need to remember a little :JVM After all background threads of a process end , Will end the operation .

Survival , Even a simple understanding , by run Whether the method has finished running

attribute	Access method
ID	getid()
name	getNanme()
state	getState()
priority	getPriority()
Background thread or not	isDaemon()
Survival	isAlive()
Whether to interrupt	isInterrupted()

 

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How to interrupt a thread

1. Use custom variables as flag bits .

2. You need to give the flag to the merchant volatile

private static boolean isQuit = false;
    public static void main(String[] args) throws InterruptedException {
        Thread thread = new Thread(()->{
            while(!isQuit){
                System.out.println("Keep running");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
        thread.start();
        thread.sleep(5000);
        System.out.println("stop running");
        isQuit = true;
        System.out.println("already stop");
    }

Self setting flag bit .

example -> Use Thread.interrupted() perhaps Thre.currentThread().isInterrupted()  Replace the custom flag bit

Thread Inside contains a Boolean The variable of type is used as a marker of whether the thread is interrupted

First, there are three ways :

Method	explain
public void interrupt()	Interrupt the thread associated with the object , If the thread is blocking , Notify... In an abnormal way
public static boolean interrupted()	Judge whether the interrupt flag bit of the current thread is set , Clear the flag bit after calling . Thread “ Interrupt state ” Cleared by this method . let me put it another way , If the method is called twice in a row , The second call will return false.
public boolean isinterrupted()	Determine whether the flag bit of the associated thread is set , Do not clear the flag bit after calling

thread There are two ways to receive notice :

1. If the thread is called wait/join/sleep And so on , with InterruptedException Notice in the form of exception , Clear interrupt flag

When there is a InterruptedException When , Whether you want to sleep in the thread depends on Catch How to write the code in . You can choose to ignore this exception , You can also jump out of the loop end thread .

2. otherwise , A break sign inside the pose is snake ,thread Can pass

Thread.interrupted() Determine whether the interrupt flag of the current thread is set , Clear interrupt flag .

Thread.currentThread().isinterrupted() Determine whether the interrupt flag of the specified thread is set , If you don't clear the interrupt flag, you will be notified in time , That is, the county is sleep You can also get it right away .