Array of Points Sorting in Java

Question

I have a class 'Point'. I want to sort an array of points, but I want to use 2 "compare" functions (I want to take 2 arrays, one with the points sorted by X and the other by Y). How can I make my class accept 2 comparing functions? Here's my code

static class Point implements Comparator<Point>{
    int x,y;
    int compareX(Point A , Point B){
        return A.x - B.x;
    }
    int compareY(Point A , Point B){
        return A.y - B.y;
    }
}

The problem is I need to implement the 'compare' function which will be used in Arrays.sort(myArray) — ivanciprian
– ivanciprian, Commented Dec 2, 2016 at 13:01

Brett Okken · Accepted Answer · 2016-12-02 13:01:44Z

2

Instead of having Point implement Comparator, have 2 Comparator constants which compare by x and y respectively.

static class Point {
  public static final Comparator<Point> X_COMPARATOR = Comparator.comparingInt(Point::getX);

  public static final Comparator<Point> Y_COMPARATOR = Comparator.comparingInt(Point::getY);
}

answered Dec 2, 2016 at 13:01

Brett Okken

6,3261 gold badge21 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

ivanciprian Over a year ago

I am not exactly sure how should I use this Comparators. This does not work: public Point sortByX(){ return Arrays.sort(this,X_COMPARATOR); }

Brett Okken Over a year ago

@epanicafrate Point is not an array. Arrays.sort takes an Object[] as the first arg. docs.oracle.com/javase/8/docs/api/java/util/…

ivanciprian Over a year ago

I meant Collections.sort, not Arrays.sort, my bad. But it still doesn't work.

Brett Okken Over a year ago

Collections.sort takes a Collection as the first arg, not a Point. What is the exact error you ar getting.

user6073886 Over a year ago

@epanicafrate the error message says that S is of type Cmap.Point[]. So its not a Collection but an Array. So you should use Arrays.sort

|

Collectives™ on Stack Overflow

Array of Points Sorting in Java

1 Answer 1

7 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Related