notify

This question already has an answer here: How can the wait() and notify() methods be called on Objects that are not threads? 9 answers I am just having hard time to understand concept behind putting wait() in Object class. For this questions sake consider if wait() and notifyAll() are in Thread class. class Reader extends Thread { Calculator c; public Reader(Calculator calc) { c = calc; } public void run() { synchronized(c) { //line 9 try { System.out.println("Waiting for calculation..."); c.wait(); } catch (InterruptedException e) {} System.out.println("Total is: " + c.total); } } public

I'm new to using wait() and notify() in Java and I'm getting an IllegalMonitorStateException. Main Code public class ThreadTest { private static Integer state = 0; public static void main(String[] args) { synchronized(state) { System.out.println("Starting thread"); Thread t = new Thread(new AnotherTest()); t.start(); synchronized(state) { state = 0; while(state == 0) { try { state.wait(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } System.out.println("State is: " + state); } } } public static class AnotherTest implements Runnable {

Is there an equivalent of PostgresQL's notify and listen in MySQL? Basically, I need to listen to triggers in my Java application server. No, there aren't any built-in functions like these yet. You need to "ping" (every 1-5 seconds) database with selecting with premade flag like "read" 0/1. After SELECT * FROM mytable WHERE read = 0 update it with read = 1 Ok, so what I found is that you can make UDF functions in mysql that can do anything but need to be written in C/C++. They can be then called from triggers on updates in database and notify your application when update happened. I saw that

I'v created a Contentprovide and implements it's update() method like this: @Override public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { final SQLiteDatabase db = mHelper.getWritableDatabase(); int count = db.update(InslideDB.FOLDER_TABLE, values, selection, selectionArgs); /* To notify the observer */ this.getContext().getContentResolver().notifyChange(URI, null); return count; } How can I get notified in my appwidget? Thanks! I'm trying this Resolver but no Log (--------------------Date Changed) print: class DataProviderObserver extends

线程状态： NEW：当一个线程被创建之初，那么此时线程就是新生状态，此状态下线程已经分配完毕内存空间。 RUNNABLE：当调用Thread.start()方法后，线程进入就绪状态，此时线程并不会马上开始执行。需要等待JVM选中并分配CPU时间才能开始执行。 RUNNING：线程被分配CPU时间后，进入执行状态，在此状态下会运行run()方法中定义的代码。 BLOCKED：当处于运行状态的线程，调用一个被阻塞的方法；试图获取一个正在被其他线程占用的锁，都会进入阻塞状态。 WAITING：等待状态。当调用了 Object.wait() ； Thread.join() ； LockSupport.park() ；方法后线程会进入等待状态。调用 Object.wait() 的线程会等待 Object.notify() 方法的调用而重新进入就绪状态。调用 Thread.join() 方法的线程会等待调用方法线程执行结束而进入结束状态。 TIMED_WAITING：固定时间等待状态。此状态下的线程都有一个固定的等待时间，通过调用 Object.wait(Long) ， Thread.sleep(Long) ， Thread.join(Long) ，都会让线程进入此状态。处于此状态的线程会等待指定的时间，然后恢复执行。 TERMINATED：线程执行结束。 状态转换图： 线程状态转换函数：

This link http://msdn.microsoft.com/en-us/library/aa772153(VS.85).aspx says: You can register up to five notification requests on a single LDAP connection. You must have a dedicated thread that waits for the notifications and processes them quickly. When you call the ldap_search_ext function to register a notification request, the function returns a message identifier that identifies that request. You then use the ldap_result function to wait for change notifications. When a change occurs, the server sends you an LDAP message that contains the message identifier for the notification request

If I just use synchronized, not wait/notify method, will it still keep thread-safe ? What's the difference ? Thx in advance. Using synchronized makes a method / block accessible by only on thread at a time. So, yes, it's thread-safe. The two concepts are combined, not mutually-exclusive. When you use wait() you need to own the monitor on that object. So you need to have synchronized(..) on it before that. Using .wait() makes the current thread stop until another thread calls .notify() on the object it waits on. This is an addition to synchronized , which just ensures that only one thread will