Java linq等效项，用于获取具有最高价值的列表中的属性

Question

Im having a list of results, ArrayList<PlacedObject> result :

for(PlacedObject po : result){

     float[] results = new float[3];

     Location.distanceBetween(lastlocation.getLatitude()
     ,lastlocation.getLongitude()
     ,Double.parseDouble(po.lat)
     ,Double.parseDouble(po.lng) ,
     results);

     po.distance = results[0];
}

After the po.distance is set, i would like to sort my list by the distance property. In c# i would use linq, but is there any similar solution in java?

Thanks

---

Current solution:

Collections.sort(result, new Comparator<PlacedObject>(){
public int  compare(PlacedObject s1, PlacedObject s2) {
    return (int) (s1.distance - s2.distance);
}
});

Answer 1

This is accomplished with the implementation of a Comparator<T> class:

A comparison function, which imposes a total ordering on some collection of objects. Comparators can be passed to a sort method (such as Collections.sort or Arrays.sort) to allow precise control over the sort order.

It could be applied to your list with Collections.sort(list, comparator) . Basically you implement your own Comparator and pass it to the method.

An implementation could for instance use an anonymous inner class:

Collections.sort(list, new Comparator<PlacedObject>() {

    @Override
    public int compare(PlacedObject po1, PlacedObject po2) {
        return Double.valueOf(po1.distance).compareTo(po2.distance);
    }
});

If you are only intersted in the maximum, as your headline indicates, there is also Collections.max which is applied in the identical way.