notify

问题 Imagine you have a typical producer-consumer pattern in Java. To be a bit more efficient you want to use notify() and not notifyAll() when a new element is added to the queue. If two producer threads invoke notify, is it guaranteed that two distinct waiting consumer threads will be awoken? Or can it be that two notify() s fired shortly after each other cause the same comsumer thread to be queued for wakeup twice? I can't find the section is the API describing how this exactly works. Does java

问题 I was getting java.lang.IllegalMonitorStateException . I referred this question and it solved my problem. The first answer is To be able to call notify() you need to synchronize on the same object. synchronized (someObject) { someObject.wait(); } /* different thread / object */ synchronized (someObject) { someObject.notify(); } My question is why we need to synchronize on the same object ad how it works? As far as my understanding goes when we say synchronized (someObject) { someObject.wait()

问题 I need to create a notification balloon message in Windows 7 from the Command prompt with custom text. I have searched Google and found shell32. 回答1: This can be done in Powershell: throw an icon ( .ico file) in a c:\temp directory or point that somewhere else. [void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") $objBalloon = New-Object System.Windows.Forms.NotifyIcon $objBalloon.Icon = "C:\temp\Folder.ico" # You can use the value Info, Warning, Error $objBalloon

问题 I have a thread that calls the wait method and can only be awoken when the notify method called from some other class: class ThreadA { public static void main(String [] args) { ThreadB b = new ThreadB(); b.start(); synchronized(b) { try { System.out.println("Waiting for b to complete..."); b.wait(); } catch (InterruptedException e) {} System.out.println("Total is: " + b.total); } } } class ThreadB extends Thread { int total; public void run() { synchronized(this) { for(int i=0;i<100;i++) {

问题 I was reading this Java: notify() vs. notifyAll() all over again. xagyg has given a good example there. I just want to know if I put notify immediately before the wait like below, will it solve the problem of deadlock? Please explain. while (buf.size()==MAX_SIZE) { notify(); wait(); // called if the buffer is full (try/catch removed for brevity) } and while (buf.size()==0) { notify(); wait(); // called if the buffer is empty (try/catch removed for brevity) // X: this is where C1 tries to re

问题 This code seems to work fine so far in testing. However I am new at multithreading and want to know if this code is ideal, since I know there is a lot of "donts" regarding concurrency. Is there a better way to make an executor for queued Runnables on a single thread? This is my first time making one so I feel inclined to believe something could be better. public class ExplosionExecutor{ private static List<Runnable> queue= new ArrayList<Runnable>(); private static Thread thread= new Thread

问题 I made a form using Intalio's AJAX Widget tool but I was confused once I wanted to add the form to a user's pool. I actually followed this tutorial from Intalio's website. In the 5th slide, they mentioned the ways of adding the form (initProcess, create and complete, notify, escalate), which look like this but no further explanations were given. So, I would like to know the differences between each one of these ways and when should I use one way and not the other. Thanks. 回答1: You use the

问题 First, this is a near duplicate of: How to differentiate when wait(long timeout) exit for notify or timeout? But it is a new follow-on question. Having this wait declaration: public final native void wait(long timeout) throws InterruptedException; It could exit by InterruptedException, or by timeout, or because Notify/NotifyAll method was called in another thread, Exception is easy to catch but... My code absolutely needs to know if the exit was from timeout or notify. (In the future, this

问题 I know that similar questions have been discussed in this site, but I have not still got further by their aid considering a specific example. I can grasp the difference of notify() and notifyAll() regarding Thread "awakeining" in theory but I cannot perceive how they influence the functionality of program when either of them is used instead of the other. Therefore I set the following code and I would like to know what is the impact of using each one of them. I can say from the start that they

问题 I want to write program using multithreading wait and notify methods in Java. This program has a stack (max-length = 5). Producer generate number forever and put it in the stack, and consumer pick it from stack. When stack is full producer must wait and when stack is empty consumers must wait. The problem is that it runs just once, I mean once it produce 5 number it stops but i put run methods in while(true) block to run nonstop able but it doesn't. Here is what i tried so far. Producer class