ThreadGroupReferenceImpl(VirtualMachine aVm,
    long aRef) 
{
        super(aVm,aRef);
        vm.state().addListener(this);
}

 protected String description() 
{
        return "ThreadGroupReference " + uniqueID();
}

 public String name() 
{
        if (name == null) {
            // Does not need synchronization, since worst-case
            // static info is fetched twice (Thread group name
            // cannot change)
            try {
                name = JDWP.ThreadGroupReference.Name.
                                     process(vm, this).groupName;
            } catch (JDWPException exc) {
                throw exc.toJDIException();
            }
        }
        return name;
}

 protected Cache newCache() 
{
        return new Cache();
}

 public ThreadGroupReference parent() 
{
        if (!triedParent) {
            // Does not need synchronization, since worst-case
            // static info is fetched twice (Thread group parent cannot
            // change)
            try {
                parent = JDWP.ThreadGroupReference.Parent.
                                 process(vm, this).parentGroup;
                triedParent = true;
            } catch (JDWPException exc) {
                throw exc.toJDIException();
            }
        }
       return parent;
}

 public  void resume() 
{
        for (ThreadReference thread : threads()) {
            thread.resume();
        }
        for (ThreadGroupReference threadGroup : threadGroups()) {
            threadGroup.resume();
        }
}

 public  void suspend() 
{
        for (ThreadReference thread : threads()) {
            thread.suspend();
        }
        for (ThreadGroupReference threadGroup : threadGroups()) {
            threadGroup.suspend();
        }
}

 public List<ThreadGroupReference> threadGroups() 
{
        return Arrays.asList((ThreadGroupReference[])kids().childGroups);
}

 public List<ThreadReference> threads() 
{
        return Arrays.asList((ThreadReference[])kids().childThreads);
}

 public String toString() 
{
        return "instance of " + referenceType().name() +
               "(name='" + name() + "', " + "id=" + uniqueID() + ")";
}

 byte typeValueKey() 
{
        return JDWP.Tag.THREAD_GROUP;
}