Callable collection methods

[meeta gaur]

import java.util.concurrent.Callable;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.HashSet;
import java.util.Set;
class CallableCollection implements Callable 
{
	Integer i=0;
	public Integer call(){   
			return ++i;
	}
	public static void main(String[] args) 
	{
		CallableCollection obj=new CallableCollection();
	
		Set s=new HashSet();
		s.add(obj);
		s.add(obj);
		s.add(obj);
		s.add(obj);
		s.add(obj);
		s.add(obj);

		Integer x=0;

		ExecutorService e=Executors.newFixedThreadPool(2);
		try{
			 x=(Integer)e.invokeAny(s);
		}
		catch(Exception ee){
					System.out.println(ee);
		}
		System.out.println(x);
		e.shutdown();
	}
}

1

Why does it always choose output 1 ?

[Matthew Brown]

You're adding the same CallableCollection 6times to a HashSet. The last 5 times have no effect, because the set won't allow duplicates.

Also, the first call to call for any CallableCollection will return 1. And you only call it once on any CallableCollection.

[meeta gaur]

import java.util.concurrent.Callable;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.HashSet;
import java.util.Set;
class CallableCollection implements Callable 
{
	String name;
	CallableCollection(String name){
		this.name=name;
	}
	public String call(){ 
			return this.name;
	}
	public static void main(String[] args) 
	{
		CallableCollection obj1=new CallableCollection("one");
		CallableCollection obj2=new CallableCollection("two");
		CallableCollection obj3=new CallableCollection("three");
		CallableCollection obj4=new CallableCollection("four");	
		CallableCollection obj5=new CallableCollection("five");	
		CallableCollection obj6=new CallableCollection("six");	
		CallableCollection obj7=new CallableCollection("seven");	

		Set s=new HashSet();
		s.add(obj1);
		s.add(obj2);
		s.add(obj3);
		s.add(obj4);
		s.add(obj5);
		s.add(obj6);
		s.add(obj7);

		String output;

		ExecutorService e=Executors.newFixedThreadPool(2);
		try{
			 output=(String)e.invokeAny(s);
	 		 System.out.println(output);
		}
		catch(Exception ee){
					System.out.println(ee);
		}
		e.shutdown();
	}
}

six

Thanks, i made some changes, now it gives me different output each time.

[meeta gaur]