Tutorial Addendum On Java - Cilia Groups

ThreadGroup Class

    

ThreadGroup: A chic represents a accumulating of Cilia altar and

    

ThreadGroup objects.

    

Features of ThreadGroup class:

    

    
• All altar of ThreadGroup chic are organized as a timberline structure.
  
      

  Each ThreadGroup item haveto accept a ancestor ThreadGroup item in the tree,
  
      

  except the basis object.
  
      



    
• The basis item of the ThreadGroup timberline is provided and managed by
  
      

  the Java Basic Apparatus (JVM).
  
      



    

Key methods:

    

    
• getParent(): Allotment the ancestor ThreadGroup object.
  
      



    
• activeCount(): Allotment the amount of alive Cilia altar in this
  
      

  ThreadGroup item and its sub-tree.
  
      



    
• activeGroupCount(): Allotment the amount of alive ThreadGroup altar in
  
      

  this ThreadGroup item and its sub-tree.
  
      



    
• enumerate(Thread[] l): Copies alive Cilia altar in this ThreadGroup
  
      

  item and its sub-tree.
  
      



    
• enumerate(ThreadGroup[] l): Copies alive ThreadGroup altar in this
  
      

  ThreadGroup item and its sub-tree.
  
      



    
• interrupt(): Calls Thread.interrupt() adjustment on
  
      

  all Cilia altar in this ThreadGroup item and its sub-tree.
  
      



    

The ThreadGroup Timberline

    

As I mentioned in the antecedent section, there is individual timberline anatomy

    

managed by the JVM to adapt all altar of ThreadGroup chic and Thread

    

class. Actuality are the rules of how this timberline is maintained:

    

    
• The basis bulge of the timberline is a ThreadGroup item called "system".
  
      



    
• The "system" cilia accumulation contains a amount of accoutrement performing
  
      

  JVM arrangement tasks.
  
      



    
• The "system" cilia accumulation contains just one ThreadGroup item called "main".
  
      



    
• The "main" cilia accumulation contains one cilia called "main", which is the
  
      

  starting cilia for the appliance program.
  
      



    
• The "main" cilia accumulation contains no additional ThreadGroup objects.
  
      



    
• If a new ThreadGroup item is created after a ancestor ThreadGroup object
  
      

  specified, it will be added into the "main" cilia group.
  
      



    
• If a new Cilia item is created after a ThreadGroup item specified,
  
      

  it will be added into the "main" cilia group.
  
      



    

Here is a simple program assuming how to use some of the methods in ThreadGroup

    

class to get advice out of the ThreatGroup tree:

    

 

    
/**

    
 * ThreadGroupTree.java

    
 * Absorb (c) 2003 by Dr.  Yang

    
 */

    
class ThreadGroupTree {

    
   accessible changeless abandoned main(String[] args) {

    
      Cilia t = Thread.currentThread();

    
      ThreadGroup g = t.getThreadGroup();

    
      g = g.getParent();

    
      printInfo(g,"");

    
      g.list();

    
   }

    
   accessible changeless abandoned printInfo(ThreadGroup g, Cord p) {

    
      System.out.println(p+"ThreadGroup name = "+g.getName());

    
      System.out.println(p+"   Has ancestor cilia accumulation = "

    
         +(g.getParent()!=null));

    
      int n = g.activeCount();

    
      System.out.println(p+"   # of alive accoutrement = "+n);

    
      Thread[] l = new Thread[n];

    
      n = g.enumerate(l, false);

    
      for (int i=0; i<n; i++) {

    
         System.out.println(p+"   Cilia name = "+l[i].getName());

    
      }  

    
      n = g.activeGroupCount();

    
      System.out.println(p+"   # of alive sub cilia groups = "+n);

    
      ThreadGroup[] s = new ThreadGroup[n];

    
      n = g.enumerate(s, false);

    
      for (int i=0; i<n; i++) {

    
         printInfo(s[i],"   "+p);

    
      }  

    
   }   

    
}