I have array with points: Point[] p = new Point[]
I want to sort it by x, and then by y. Meaning, If I have
Point A = (1, 2)
Point B = (2, 1)
Point C = (1, 3)
Point D = (2, 2)
After sorting, I will get: [(1,2), (1,3), (2,1), (2,2)]
I try to use Arrays.sort(), but point isn't comparable. There is an easy way to do that?
You can use Arrays.sort with a custom Comparer<Point>:
Arrays.sort(p, new Comparator<Point>() {
int compare(Point a, Point b) {
int xComp = Integer.compare(a.x, b.x);
if(xComp == 0)
return Integer.compare(a.y, b.y);
else
return xComp;
}
});
Sidenotes:
Point objects may be null, you must handle this
in compareTo.Point is not an AWT point but your own
class, you'd better let it implement Comparable.
Arrays.sort before. It's just an overload for arrays of non-Comparable objects.you can try (pseudo code).
Arrays.sort(p, new Comparator<Point >() {
public int compare(Point p1, Point p2) {
//here operations and return
}
});
Let Point implement the Comparable interface, and override its compareTo method to suit your needs.
@Override
public int compareTo(Point p) {
if (this.x != p.x) {
return Integer.compareTo(this.x, p.x);
} else {
return Integer.compareTo(this.y, p.y);
}
}
Read more: http://javarevisited.blogspot.com/2012/01/how-to-sort-arraylist-in-java-example.html#ixzz2S2i9k5V3
This requires editing the Point class. If that's not possible, see other answers for alternative solutions.
Since Point does not implement comparable you can create your own class for comparison:
public class Sorter implements Comparator
{
public int compare(Object o1, Object o2)
{
Point pointOne = (Point)o1;
Point pointTwo = (Point)o2;
return ((pointOne.getX()+pointOne.getY())+"").compareTo(((pointTwo.getX()+pointTwo.getY())+""));
}
}
Then yo can use this Sorter class:
void mySortingFunc(Point[] points)
{
Arrays.sort(points, new Sorter());
}
ComparatororComparableinterface.