J2SE Basics: 13. Multithreaded programming

1: Processes and Threads

Process: Runs a program in which the program allocates the running space in memory. A process was started in memory.

Threads: Running in a process. Multiple threads can be switched between each other.

Main thread

Child Threads: Child threads are assigned from the main thread.

2: Importance of the main thread.

3: Creating Multithreading in Java

1: Inherit the Thread class:

2: Implement Runable Interface:

The difference between inheriting the thread class and implementing the Runable interface:

Java only supports single inheritance, and once a class inherits the thread class, it can no longer inherit other classes.

4:seleep method



5:thread.join method: If a thread joins another thread, the thread must wait for another thread


The Run method runs end (thread end). Method of adjusting = =






Thread.yield method: Give up the CPU resources, let the other threads execute.


Thread.setpriority (): Sets the priority of the thread. Priority, the longer the CPU is scheduled.
Max = 10
Normal = 5
Min = 0;
The value range is between 0---10.


Thread.seleep (): The Sleep of the thread. Unlike yield, it is dormant. Can be awakened.




Methods to stop a thread:

The old way of realizing it before

Stop/destory method. Causes deadlocks (to understand deadlocks in a way that combines iterators and collections)

Now the new way:

6: Why to use thread synchronization:

A: When multiple threads access a resource at the same time, it causes the resource data to be out of sync. Therefore, the resources are locked.

The lock-up process is that only one thread can access the resource when the threads are concurrent. So called

Synchronization of Threads.

7: The concept of the lock


8: What exactly locks:

Locks the object and class where the current method (current variable) resides.

Synchronized (synchronous)

Asynchronized (asynchronous)

9: How to Implement Thread synchronization:

A: Method Synchronization.

B: code block synchronization:

Method synchronization differs from code block synchronization:

Method synchronization: Locks the object on which the current method resides. Therefore, the entire method is executed until it is complete, locking the current object.

Code block synchronization: The lock on an object is only a block of code that executes the synchronized part. Other blocks of code will also appear

Current thread synchronization issues.

Synchronized (this) {

Count = count + 1;

try {

Thread.Sleep (2000);

} catch (Exception e) {

E.printstacktrace ();

}

System.out.println ("Current thread =" + Thread.CurrentThread (). GetName ()

+ ", count value =" + count);

}

System.out.println (count);

10: Coarse grain size of the lock:

The coarse granularity of the lock can only change the size of the lock in code block synchronization. There is no way to change the method's synchronization.

11: Collaboration between Threads:

Wait ();/notify ();

J2SE Basics: 13. Multithreaded programming