java 集合排序异常Exception in thread "main" java.lang.IllegalArgumentException: Comparison method violate

报错

Exception in thread "main" java.lang.IllegalArgumentException: Comparison method violates its general contract!

原因在于比较的值中有NaN，所以不能用下面的compareTo，要用Double类中的compareTo

http://stackoverflow.com/questions/9469308/java-error-comparison-method-violates-its-general-contract

NaN（ A constant holding a Not-a-Number (NaN) value of type double.）

 public int compareTo(Data o) {     
 if(distance > o.getDistance()){
          return -1;
   }else if (distance < o.getDistance()){
         return 1;
      }else
        return 0;
}

改为

    public int compareTo(Data o) {
        return -Double.compare(o.distance, this.distance);
}