Daemon thread instance in multithread termination in Java language

There are two types of threads in Java: user threads and guard (service) threads. Through thread Set setdaemon (false) to user thread; Through thread Setdaemon (true) is set as the daemon thread; If not set, it defaults to user thread.

End single thread with thread Interrupt() method. If multithreading ends, you need to set the daemon thread. When there are no user threads, the daemon threads will all terminate (it can be understood that the daemon thread is the service thread, the user thread is the serviced thread, and the user thread (the serviced thread) will all disappear, so the service thread will have no meaning and terminate automatically)

example:

When the last sentence system out. When println ("over"), the user thread (main program) ends; the two daemon threads that continuously output information in the background eternal loop will also terminate automatically.

Another common question: after all non daemon threads in Java end, all daemon threads automatically exit, right?

Reference answer:

The only function of a daemon thread is to serve other threads When only the daemon thread is left, the virtual machine exits "(from: Java core technology). Now there are no non daemon threads, so there is no need for daemon to provide services.