java使用迭代器对象循环throuh arraylist并检查它是否高于某个值

Question

我有一个静态方法，我需要完成它

我要做的是使用迭代器检查y坐标是否大于最大值，并返回该值。这是我现在拥有的

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;
}

当我运行代码时，会出现一个语法错误：

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是一个列表，因此不能对其调用getY（）。您需要首先从对pointIterator的调用中获取Point对象。然后对其调用getY（）方法

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

您还可以通过使用流和删除整个样板代码来实现相同的功能

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

Answer 2

将next()的结果存储在变量中

Point currentPoint = pointIterator.next();

检查当前highestPoint是否为null。如果是，请将currentPoint设置为最高值：

if(highestPoint == null)
    highestPoint = currentPoint;

否则，将最高点与电流进行比较：

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

不需要int highest。你的最终结果是：

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;
}