DemographicInformation infoB = (DemographicInformation)demographicData.get(typeA);
DemographicInformation infoB = (DemographicInformation)demographicData.get(typeB);
    public int compare (Object a, Object b) {      if (a == null) return 1;      if (b == null) return -1;      if ((a instanceof VM_Type) && (b instanceof VM_Type)) {        VM_Type typeA = (VM_Type) a;        VM_Type typeB = (VM_Type) b;        DemographicInformation infoA = (DemographicInformation)demographicData.get(typeA);        if (infoA == null) return 1;        DemographicInformation infoB = (DemographicInformation)demographicData.get(typeA);        if (infoB == null) return -1;        if (infoA.size > infoB.size) return -1;        if (infoA.size < infoB.size) return 1;        return 0;      }      return 0;    }