Threads - Beginning Java 8 Language Features - page 213

Listing 6-18. A Non-Daemon Thread Example
// NonDaemonThread.java
package com.jdojo.threads;
public class NonDaemonThread {
public static void main(String[] args) {
Thread t = new Thread(NonDaemonThread::print);
// t is already a non-daemon thread because the "main" thread that runs
// the main() method is a non-daemon thread. You can verify it by using
// t.isDaemon() method. It will return false.
// Still we will use the following statement to make it clear that we
// want t to be a non-daemon thread.
t.setDaemon(false);
t.start();
System.out.println("Exiting main method");
}
public static void print() {
int counter = 1;
while(true) {
try {
System.out.println("Counter:" + counter++);
Thread.sleep(2000); // sleep for 2 seconds
}
catch(InterruptedException e) {
e.printStackTrace();
}
}
}
}
Exiting main method
Counter:1
Counter:2
...
Am I Interrupted?
You can interrupt a thread that is alive by using the interrupt() method. This method invocation on a thread is just
an indication to the thread that some other part of the program is trying to draw its attention. It is up to the thread how
it responds to the interruption. Java implements the interruption mechanism using an interrupted status flag for
every thread.
A thread could be in one of the two states when it is interrupted: running or blocked. If a thread is interrupted
when it is running, its interrupted status is set by the JVM. The running thread can check its interrupted status by
calling the Thread.interrupted() static method, which returns true if the current thread was interrupted. The
call to the Thread.interrupted() method clears the interrupted status of a thread. That is, if you call this method
again on the same thread and if the first call returned true , the subsequent calls will return false , unless the thread is
interrupted after the first call but before the subsequent calls.