I have a few questions on multithreading and waiting in Java on the following code.
/*
* Taken from
* https://www.wiley.com/en-us/Java+Programming%3A+24+Hour+Trainer%2C+2nd+Edition-p-9781118951453
*/
public class TestThreads3LambdaWait {
public static void main(String args[]) {
// Lambda expression for Market News
Runnable mn = () -> {
try {
for (int i = 0; i < 10; i++) {
Thread.sleep (1000); // sleep for 1 second
System.out.println( "The market is improving " + i);
}
} catch(InterruptedException e ) {
System.out.println(Thread.currentThread().getName()
+ e.toString());
}
};
Thread marketNews = new Thread(mn, "Market News");
marketNews.start();
// Lambda expression for Portfolio
Runnable port = () -> {
try {
for (int i = 0; i < 10; i++) {
Thread.sleep (700); // Sleep for 700 milliseconds
System.out.println( "You have " + (500 + i) +
" shares of IBM");
}
} catch(InterruptedException e ) {
System.out.println(Thread.currentThread().getName()
+ e.toString());
}
};
Thread portfolio = new Thread(port,"Portfolio data");
portfolio.start();
TestThreads3LambdaWait thisInstance = new TestThreads3LambdaWait();
synchronized (thisInstance) {
try {
thisInstance.wait(15000);
System.out.println("finished wait");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println( "The main method of TestThreads3Lambda is finished");
}
}
mn
and port
call notify()
when they finish executing?main()
is static, the code in main()
is not tied to a specific object.)thisInstance
, which is not tied to main()
since main()
is static). Is it because all TestThreads3LambdaWait
objects are notified because mn
and port
are in a static method and thus tied to every instance?notify(All)
anywhere inside it.Thread.sleep(15000)
would also do it, which is effectively what your wait
call does, given that nobody notifies.