43. Daemon Threads and Join methods

1. Daemon thread (Background thread):
when we use a software, some software will let us do not know the situation to download something, then this is the background thread.
generally used to increase the amount of software downloaded (that is, to earn some advertising costs)
            
Setdaemon (Boolean B) setting is a daemon thread
Isdaemon () returns whether it is a daemon thread (true no false)
Note: When the program stops running, the daemon thread must also stop

let's simulate using QQ, then download a software in the background

 Public classDemo11Implementsrunnable{@Override Public voidrun () { for(inti = 1; I <= 100; i++) {System.out.println ("Current Download" +i+ "%"); }    }     Public Static voidMain (string[] args) {Demo11 d=NewDemo11 (); Thread Thread=NewThread (d); Thread.setdaemon (true);//Set as daemon threadThread.Start (); //QQ Program stops when I is 100         for(inti = 0; I < 100; i++) {System.out.println ("Use QQ" +i); }    }}

2.join join:

When you use this method in a thread task body (run), you must wait until the thread that calls the Join method finishes the task before the task body can continue execution

code example:

classThread2Implementsrunnable{@Override Public voidrun () { for(inti = 0; I < 20; i++) {System.out.println (Thread.CurrentThread (). GetName ()+":"+i); }        }} Public classDemo12Implementsrunnable{@Override Public voidrun () { for(inti = 0; I < 100; i++) {            if(i==30) {Thread2 T=NewThread2 (); Thread Thread=NewThread (t, "joined thread");                Thread.Start (); Try{thread.join ();//Join a thread}Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace (); }} System.out.println (Thread.CurrentThread (). GetName ()+":"+i); }    }         Public Static voidMain (string[] args) {Demo12 d=NewDemo12 (); Thread Thread=NewThread (d, "joined thread");    Thread.Start (); }}

43. Daemon Threads and Join methods