Java Object notifyAll() Method
Java Object ClassThe Object notifyAll() method is used to wake up all threads waiting on that object.
The notifyAll() method is similar to thenotify() method,The difference is that the notifyAll() method wakes up all threads waiting on this object's monitor, while the notify() method wakes up one thread.
If the current thread is not the owner of the object's monitor, calling the notifyAll() method will also throw anIllegalMonitorStateExceptionexception.
Syntax
public final void notifyAll()
Parameters
None 。
Return Value
No return value.
Example
The following example demonstrates the use of the notifyAll() method:
Example
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
public class ExampleTest {
private List synchedList;
public ExampleTest() {
//Create a synchronized list
synchedList = Collections.synchronizedList(new LinkedList());
}
//Delete an element from the list
public String removeElement() throws InterruptedException {
synchronized (synchedList) {
//Wait if the list is empty
while (synchedList.isEmpty()) {
System.out.println("List is empty...");
synchedList.wait();
System.out.println("Waiting...");
}
String element = (String) synchedList.remove(0);
return element;
}
}
//Add an element to the list
public void addElement(String element) {
System.out.println("Opening...");
synchronized (synchedList) {
//Add an element and notify that the element exists
synchedList.add(element);
System.out.println("New Element:'" + element + "'");
synchedList.notifyAll();
System.out.println("notifyAll called!");
}
System.out.println("Closing...");
}
public static void main(String[] args) {
final ExampleTest demo = new ExampleTest();
Runnable runA = new Runnable() {
public void run() {
try {
String item = demo.removeElement();
System.out.println("" + item);
} catch (InterruptedException ix) {
System.out.println("Interrupted Exception!");
} catch (Exception x) {
System.out.println("Exception thrown.");
}
}
};
Runnable runB = new Runnable() {
//Perform the add element operation and start the loop
public void run() {
demo.addElement("Hello!");
}
};
try {
Thread threadA1 = new Thread(runA, "Google");
threadA1.start();
Thread.sleep(500);
Thread threadA2 = new Thread(runA, "Example");
threadA2.start();
Thread.sleep(500);
Thread threadB = new Thread(runB, "Taobao");
threadB.start();
Thread.sleep(1000);
threadA1.interrupt();
threadA2.interrupt();
} catch (InterruptedException x) {
}
}
}
The output of the above program is:
List is empty... List is empty... Opening... New Element:'Hello!' notifyAll called! Closing... Waiting... Waiting... List is empty... Hello! Interrupted Exception!
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