'Back-End/Java_1'에 해당되는 글 48건

Daemon Thread

- Daemon Thread is a service provider thread that provides services to the user thread

- Its life depend on the mercy of user thread i.e. all the user threads dies, JVM terminates this thread automatically

- gc, finalizer etc..

1. Points to remember for Daemon Thread

- It provides services to user threads for background supporting tasks

- Its life depends on user thread

- It is a low priority thread

2. Why JVM terminates the daemon thread if there is no user thread?

- The sole purpose of the daemon thread is that it provides services to user thread for background supporting task

- If there is no user thread, we don't need daemon threads

3. Methods for Daemon thread by Thread class

1) public void setDaemon(boolean status)

- It is used to mark the current thread as daemon thread or user thread

2) public boolean isDaemon()

- It is used to check that current is daemon

4. Example

public class Daemon extends Thread{ public void run(){ if(Thread.currentThread().isDaemon()){ System.out.println("daemon thread"); }else{ System.out.println("user thread"); } } public static void main(String[]args){ Daemon t1 = new Daemon(); Daemon t2 = new Daemon(); Daemon t3 = new Daemon(); t1.setDaemon(true); t1.start(); t2.start(); t3.start(); } }

Thread Priority

- Each thread have a priority

- Thread schedular schedules the threads according to their priority(preemptive scheduling)

1. 3 constants defined in Thread

- public static int MIN_PRIORITY

- public static int NORM-PRIORITY

- public static int MAX-PRIORITY

- Default is 5(NORM), MIN is 1, MAX is 10

2. Example

public class priority extends Thread{ public void run(){ System.out.println("running thread name:"+Thread.currentThread().getName()); System.out.println("running thread priority:"+Thread.currentThread().getPriority()); } public static void main(String[]args){ priority t1 = new priority(); priority t2 = new priority(); t1.setPriority(Thread.MIN_PRIORITY); t2.setPriority(Thread.MAX_PRIORITY); t2.start(); t1.start(); } }

Naming Thread

- The Thread class provides methods to change and get them name of a thread

- Each thread has a name

- we can change the name of the thread by using setName()

1. Syntax

- public String getName()

- public void setName(String name)

2. Example

public class Name extends Thread{ public void run(){ System.out.println("running"); } public static void main(String[]args){ Name t1 = new Name(); Name t2 = new Name(); System.out.println("Name t1: "+t1.getName()); System.out.println("Name t2: "+t2.getName()); t1.start(); t2.start(); t1.setName("Kyle"); System.out.println("After Name t1: "+t1.getName()); } }

Joining a thread

- join() waits for a thread to die

1. Syntax

- public void join()throws InterruptedException

- public void join(long milliseconds)throws InterruptedException

2. Example

public class join extends Thread{ public void run(){ for(int i = 0 ; i < 5; i++){ try{ Thread.sleep(500); }catch(Exception e){ System.out.println(e); } System.out.println(i); } } public static void main(String[]args){ join t1 = new join(); join t2 = new join(); join t3 = new join(); t1.start(); try{ t1.join(); }catch(Exception e){ System.out.println(e); } t2.start(); t3.start(); } }