TreeSet Comparator in java

**Aaliya Seth** · 23-02-2010

Hello,
I have a problem in using the TreeSet in my program, when I try to compile it, I get an error.
Here is my code:

Code:

Public class test implements Comparator
{
 
    /**
     *
     */
 
    Public int compares(Object arg0, Object arg1)
    {
        can c0 = (can) arg0;
        can c1 = (can) arg1;
        
      double d = c1.getScoreApresEtapeHarmonisation() - C2.getScoreApresEtapeHarmonisation();
        
        if (d < 0) return +1;
        if (d> 0) return -1;
        if (== d 0)
        {
            double[] scr1 = c1.cal(); 
            double[] scr2 = c2.cal();
            
            / / Comparing scores weighted by dominance. 
            for ( int i = 1; I < 5; I + + ) 
            {
                if (scr1[i] - ScorePondere2[2] < 0) return +1;
                if (scr1[i] - ScorePondere2[2] > 0) return -1;
            }
        }
        return 0;
    }     
        
        }
  }

**Linux-Us** · 23-02-2010

Hello,
Have you redefine the equals method, because if the ex-breaking are equals, there are chances that the TreeSet regarded as the objects are identical and it does not add. If it's not that you can always try using a different parameter in tone compared to differentiate the ex-breaking (the name of such candidate) If it does not always show us the class "can", it could perhaps enlighten us.

**Gunner 1** · 23-02-2010

Hey,
I am new to this concept , even i need a help in this , but I have a code with me , check it out.

Code:

  Public boolean equals(Other object)
    {
        if (!(other instanceof can)) return false;
        can castOther = (can) other;
        return new EqualsBuilder().append(this.getID(), CastOther.getID()).isEqual();
    }

**HardWeaR** · 23-02-2010

Hello,
In the javadoc says that the equals method must be consistent with compareTo. In fact the TreeSet uses the method of the comparator to sort, if the comparator returns 0 for its objects are identical and it does not add the new object. If you have unique IDs you could use them in your comparator to return a nonzero value in case of a tie. You classify them by ID in case of increasing equality. It is a good solution that respects the logic of the method of the comparator.

**GlassFish** · 23-02-2010

Hello,
You can shorten your code something like this

Code:

return c1.getId() - C2-getId();

Instead of using this

Code:

return 0;

Hope this will help you, just have a try at it and see if it works for you, if not then post back your code and the error you get while compiling the code.

**Aaliya Seth** · 23-02-2010

Hello,
Can I use in the code, something like this.

Code:

ArrayList arr = new ArrayList(dEtape.getCandidatsInscritEtape());
Collections.fate(ArrayList new con());	
		
	/ / Get the iterator
		iter = ArrayList.iterator();

Is this going to help me, please advice. I am in need of this code and you will have to help me out. Thanks in advance.