Array.sort(Object[], comparator) problems

Question

I have been trying for days to figure out how to sort my array of geneInfo ono the field score1.
when i try to use Arrays.sort(gInfo, new score1Comp()) it turns all of the array null.
class score1Comp implements Comparator
public int compare(Object o1, Object o2)
geneInfo g1 = (geneInfo)o1;
geneInfo g2 = (geneInfo)o2;
// added these checkers to get rid of nullPointerException, but checked to see that most are non null
if(g1==null&&g2==null)
return 0;
if(g1==null)
return -1;
if(g2==null)
return 1;
if(g1.getScore1() == g2.getScore1())
return 0;
else
double temp = g1.getScore1() - g2.getScore1();
System.out.println("score g1 - score g2: " + temp);
System.out.println("rounded: " + (int)Math.round(temp));
return (int)Math.round(temp);
public boolean equals(Object obj)
return obj.equals (this);
}

Answer 1

You have sorting your array with null to be the least on value object. For example here:
MyObject[] objs = new MyObject[1000];
objs[0] = new MyObject(3);
objs[1] = new MyObject(2);
objs[2] = new MyObject(1);
Arrays.sort(objs, new score1Comp());Guess what the result would be? Your array would have the first 997 elements become null and the last 3 would be sorted to (1), (2), (3).
So the cause is how your Comparator treats the null value. The solution could be to make sure your sorting array is filled correctly, or reverse the return 1/-1 for the null treatment.
--lichu