Key in HashSet

Question

I want to insert my customized objects into HasSet but same time i want to ensure that it should not accept duplicate objects and also i want to insert the objects in sorted manner but the constraint here is i can o use only HashSet, so how i can do this.

Answer 1

Thanks for your valuable suggestion... i have tried following code but
its not preserving sorting..
class Car implements Comparable
private int x;
public int getX()
return x;
public int compareTo(Object o1)
System.out.println("conpare() called x="+x+"o1="+((Car)o1).getX());
if(x<((Car)o1).getX())
          return 1;
     else if(x>((Car)o1).getX())
          return -1;
     else return 0;
public Car(int x)
     this.x=x;
public boolean equals(Object o)
          System.out.println("equals Called");
          compareTo(o);
          if( ((Car)o).getX()==x )
               return true;
return false;
public int hashCode()
System.out.println("HashCode Called x="+x);
equals(this);
return x*2;
public String toString()
return String.valueOf(x);
public class HashTest2
public static void main(String[] argv)
Car c2= new Car(2);
Car c1 = new Car(1);
HashSet SET = new HashSet();
SET.add(new Car(3));
SET.add(c1);
SET.add(c2);
SET.add(new Car(3));
SET.add(new Car(13));
SET.add(new Car(10));
for(Object c: SET)
     System.out.println((Car)c);
}