Using iterator object to loop throuh arraylist and check if it is higher than a value

Question

I have a static method and I am required to complete it.

What I have to do is use an Iterator to check if the y coordinate is greater than highest value and return that value. Here's what I have now.

import java.awt.*;

public static Point highestPoint(List<Point> points) {
Iterator<Point> pointIterator = points.iterator();
int highest = 0;
Point highestPoint = null;
while (pointIterator.hasNext()) {
   pointIterator.next()
    if (points.getY() > highest) {
      highest = points.get(Y);
  }

}


return highestPoint;
}

When I run my code, I get a syntax error saying this:

Main.java:12: error: cannot find symbol
  if (points.getY() > highest) {
            ^
symbol:   method getY()
location: variable points of type List<Point>
Main.java:13: error: cannot find symbol
      highest = points.getY();
                      ^
symbol:   method getY()
location: variable points of type List<Point>
2 errors

Answer 1

points is a List and you cannot hence call getY() on it. You need to get the Point object first from the call to pointIterator.next() and then call getY() method on it.

while (pointIterator.hasNext()) {
    Point point = pointIterator.next();
    if (point.getY() > highest) {
        highest = point.get(Y);
     }
}

You can also achieve the same using streams and by removing the entire boilerplate code

Point highest = points.stream().max((p1, p2) -> p1.getY() > p2.getY() ? 1 : -1).get();

Answer 2

Store the result of next() in a variable

Point currentPoint = pointIterator.next();

Check if the current highestPoint is null . If so, set the currentPoint as the highest:

if(highestPoint == null)
    highestPoint = currentPoint;

Otherwise, compare the highest point to the current:

if(highestPoint == null)
    highestPoint = currentPoint;
else if(highestPoint.getY() < currentPoint.getY())
    highestPoint = currentPoint;

No need for int highest . Your final result would be:

public Point highestPoint(List<Point> points) {
    Point highestPoint = null;

    Iterator<Point> pointIterator = points.iterator();
    while(pointIterator.hasNext()) {
        Point currentPoint = pointIterator.next();

        if(highestPoint == null || highestPoint.getY() < currentPoint.getY())
            highestPoint = currentPoint;
    }

    return highestPoint;
}