Java
javaTutorial
Discuss the essential difference between notify() and notifyAll() through examples
Discuss the essential difference between notify() and notifyAll() through examples
notify() and notifyAll() are both methods used by the Object object to notify threads waiting for the object. The biggest difference between the two is:
notifyAll causes all threads that were originally waiting to be notified on the object to exit the wait state and become waiting for the lock on the object. Once the object is unlocked, they will To compete.
notify is much more civilized. It just selects a wait state thread to notify and makes it obtain the lock on the object, but does not disturb other threads that are also waiting to be notified by the object. When the first thread finishes running After releasing the lock on the object, if the object does not use the notify statement again, even if the object is already idle, other threads waiting in the wait state will continue to be in the wait state because they have not been notified by the object until the object issues a notify. Or notifyAll, they are waiting to be notified or notifyAll, not the lock.
The following is a good example:
import java.util.*;
class Widget...{}
class WidgetMaker extends Thread...{
List<Widget> finishedWidgets=new ArrayList<Widget>();
public void run()...{
try...{
while(true)...{
Thread.sleep(5000);//act busy
Widget w=new Widget();
//也就是说需要5秒钟才能新产生一个Widget，这决定了一定要用notify而不是notifyAll
//因为上面两行代码不是同步的，如果用notifyAll则所有线程都企图冲出wait状态
//第一个线程得到了锁，并取走了Widget（这个过程的时间小于5秒，新的Widget还没有生成）
//并且解开了锁，然后第二个线程获得锁(因为用了notifyAll其他线程不再等待notify语句
//，而是等待finishedWidgets上的锁，一旦锁放开了，他们就会竞争运行)，运行
//finishedWidgets.remove(0)，但是由于finishedWidgets现在还是空的，
//于是产生异常
//***********这就是为什么下面的那一句不能用notifyAll而是要用notify
synchronized(finishedWidgets)...{
finishedWidgets.add(w);
finishedWidgets.notify(); //这里只能是notify而不能是notifyAll
}
}
}
catch(InterruptedException e)...{}
}
public Widget waitForWidget()...{
synchronized(finishedWidgets)...{
if(finishedWidgets.size()==0)...{
try...{
finishedWidgets.wait();
}
catch(InterruptedException e)
...{}
}
return finishedWidgets.remove(0);
}
}
}
public class WidgetUser extends Thread...{
private WidgetMaker maker;
public WidgetUser(String name,WidgetMaker maker)...{
super(name);
this.maker=maker;
}
public void run()...{
Widget w=maker.waitForWidget();
System.out.println(getName()+"got a widget");
}
public static void main(String[] args) ...{
WidgetMaker maker=new WidgetMaker();
maker.start();
new WidgetUser("Lenny",maker).start();
new WidgetUser("Moe",maker).start();
new WidgetUser("Curly",maker).start();
}
}Related articles:
Detailed comparison of java notify and notifyAll
Two ways to collaborate between threads in java concurrency: wait, notify, notifyAll and Condition
##Correct usage of wait, notify and notifyAll
The above is the detailed content of Discuss the essential difference between notify() and notifyAll() through examples. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
What are the basic requirements for c language functions
Apr 03, 2025 pm 10:06 PM
C language functions are the basis for code modularization and program building. They consist of declarations (function headers) and definitions (function bodies). C language uses values to pass parameters by default, but external variables can also be modified using address pass. Functions can have or have no return value, and the return value type must be consistent with the declaration. Function naming should be clear and easy to understand, using camel or underscore nomenclature. Follow the single responsibility principle and keep the function simplicity to improve maintainability and readability.
How to set password protection for export PDF on PS
Apr 06, 2025 pm 04:45 PM
Export password-protected PDF in Photoshop: Open the image file. Click "File"> "Export"> "Export as PDF". Set the "Security" option and enter the same password twice. Click "Export" to generate a PDF file.
The difference between H5 and mini-programs and APPs
Apr 06, 2025 am 10:42 AM
H5. The main difference between mini programs and APP is: technical architecture: H5 is based on web technology, and mini programs and APP are independent applications. Experience and functions: H5 is light and easy to use, with limited functions; mini programs are lightweight and have good interactiveness; APPs are powerful and have smooth experience. Compatibility: H5 is cross-platform compatible, applets and APPs are restricted by the platform. Development cost: H5 has low development cost, medium mini programs, and highest APP. Applicable scenarios: H5 is suitable for information display, applets are suitable for lightweight applications, and APPs are suitable for complex functions.
Concept of c language function
Apr 03, 2025 pm 10:09 PM
C language functions are reusable code blocks. They receive input, perform operations, and return results, which modularly improves reusability and reduces complexity. The internal mechanism of the function includes parameter passing, function execution, and return values. The entire process involves optimization such as function inline. A good function is written following the principle of single responsibility, small number of parameters, naming specifications, and error handling. Pointers combined with functions can achieve more powerful functions, such as modifying external variable values. Function pointers pass functions as parameters or store addresses, and are used to implement dynamic calls to functions. Understanding function features and techniques is the key to writing efficient, maintainable, and easy to understand C programs.
Why do you need to call Vue.use(VueRouter) in the index.js file under the router folder?
Apr 05, 2025 pm 01:03 PM
The necessity of registering VueRouter in the index.js file under the router folder When developing Vue applications, you often encounter problems with routing configuration. Special...
What are the differences and connections between c and c#?
Apr 03, 2025 pm 10:36 PM
Although C and C# have similarities, they are completely different: C is a process-oriented, manual memory management, and platform-dependent language used for system programming; C# is an object-oriented, garbage collection, and platform-independent language used for desktop, web application and game development.
How to use XPath to search from a specified DOM node in JavaScript?
Apr 04, 2025 pm 11:15 PM
Detailed explanation of XPath search method under DOM nodes In JavaScript, we often need to find specific nodes from the DOM tree based on XPath expressions. If you need to...
What are the different ways of promoting H5 and mini programs?
Apr 06, 2025 am 11:03 AM
There are differences in the promotion methods of H5 and mini programs: platform dependence: H5 depends on the browser, and mini programs rely on specific platforms (such as WeChat). User experience: The H5 experience is poor, and the mini program provides a smooth experience similar to native applications. Communication method: H5 is spread through links, and mini programs are shared or searched through the platform. H5 promotion methods: social sharing, email marketing, QR code, SEO, paid advertising. Mini program promotion methods: platform promotion, social sharing, offline promotion, ASO, cooperation with other platforms.
