这里是一个解决方案,我的同事和我想出了。希望它可以帮助别人。
public class PolygonHelper {
public Polygon makePolygon(List<Rectangle> rectangles){
List<Point> points = calcPoints(rectangles);
return new Polygon(points);
}
private List<Point> calcPoints(List<Rectangle> rectangles) {
List<Point> ret = new ArrayList<>();
List<Float> yCoords = new ArrayList<>(getAllYCoords(rectangles));
yCoords.sort(Comparator.naturalOrder());
float previousLeftCoord = 0;
float previousRightCoord = 0;
for(float yCoord : yCoords) {
System.out.println("Considering yCoords "+ yCoord);
float minimumXLeftCoord = minXLeftCoord(yCoord, rectangles);
float maximumXRightCoord = maxXRightCoord(yCoord, rectangles);
System.out.println("min X: "+minimumXLeftCoord);
System.out.println("max X: "+maximumXRightCoord);
if(yCoord == yCoords.get(0)) {
ret.add(new Point(minimumXLeftCoord, yCoord));
ret.add(new Point(maximumXRightCoord, yCoord));
} else {
if(minimumXLeftCoord!=previousLeftCoord) {
ret.add(0, new Point(previousLeftCoord, yCoord));
ret.add(0, new Point(minimumXLeftCoord, yCoord));
} else {
ret.add(0, new Point(minimumXLeftCoord, yCoord));
}
if(maximumXRightCoord!=previousRightCoord) {
ret.add(new Point(previousRightCoord, yCoord));
ret.add(new Point(maximumXRightCoord, yCoord));
} else {
ret.add(new Point(maximumXRightCoord, yCoord));
}
}
previousLeftCoord = minimumXLeftCoord;
previousRightCoord = maximumXRightCoord;
System.out.println(ret);
}
return ret;
}
private Set<Float> getAllYCoords(List<Rectangle> rectangles) {
List<Float> allBottomYCoords = rectangles.stream().map(rectangle -> rectangle.getBottom().getY()).collect(Collectors.toList());
List<Float> allTopYCoords = rectangles.stream().map(rectangle -> rectangle.getTop().getY()).collect(Collectors.toList());
Set<Float> allCoords = new HashSet<>();
allCoords.addAll(allTopYCoords);
allCoords.addAll(allBottomYCoords);
return allCoords;
}
private float minXLeftCoord(Float y, List<Rectangle> rectangles) {
return rectanglesAtY(y, rectangles).stream().map(rect -> rect.getLeft().getX()).min(Comparator.naturalOrder()).get();
}
private float maxXRightCoord(Float y, List<Rectangle> rectangles) {
return rectanglesAtY(y, rectangles).stream().map(rect -> rect.getRight().getX()).max(Comparator.naturalOrder()).get();
}
private List<Rectangle> rectanglesAtY(Float y, List<Rectangle> rectangles) {
List<Rectangle> rectsAtYExcBottomLines = rectsAtYExcBottomLines(y, rectangles);
if(rectsAtYExcBottomLines.size()>0) {
// there are rectangles that are not closing here, so ignore those that are closing.
return rectsAtYExcBottomLines;
} else {
// there are only rectangle bottom lines so we need to consider them.
return rectsAtYIncBottomLines(y, rectangles);
}
}
private List<Rectangle> rectsAtYExcBottomLines(Float y, List<Rectangle> rectangles) {
return rectangles.stream()
.filter(rect -> rect.getTop().getY()<=y && rect.getBottom().getY()>y).collect(Collectors.toList());
}
private List<Rectangle> rectsAtYIncBottomLines(Float y, List<Rectangle> rectangles) {
return rectangles.stream()
.filter(rect -> rect.getTop().getY()<=y && rect.getBottom().getY()==y).collect(Collectors.toList());
}
}
您是否允许使用内置API或此类学校作业? – MadProgrammer
哪些内置API?没有这不是一个学校的任务 - 这是我必须做的工作的一部分。为什么这个问题已经被拒绝了?! – robbie70
因为你要求人们给你答案,而不是自己编码。 – UnknowableIneffable