java class method 代码具体实现

我正在做cs61B的一个project，需要生成一个2D world，看到这篇文章，原文链接：https://blog.csdn.net/lindaicoding/article/details/119202956
里面有一个Directions类，direction包括上下左右，左上左下右上右下8个方向，我不知道这个Directions.getDirections().values()是怎么回事，我想知道这个getDirections() 和values的代码。

for(Point point : FloorPoints) {
            for(Tuple direction : Directions.getDirections().values()) {
                Point p = new Point(point.x + (int)direction.getFirst(), point.y + (int)direction.getSecond());
                if(p.x < 0 || p.y < 0 || p.x >=WIDTH || p.y >= HEIGHT) continue;
                if(world[p.x][p.y] == Tileset.FLOOR) continue;
                if(world[p.x][p.y] == Tileset.WALL) continue;
                
                WallPoints.add(new Point(p.x, p.y));
            }

public class Directions {
    private static final Map<String, Tuple<Integer, Integer>> directions = new HashMap<>();

    static {
        directions.put("UP", new Tuple<>(0, 1));
        directions.put("DOWN", new Tuple<>(0, -1));
        directions.put("LEFT", new Tuple<>(-1, 0));
        directions.put("RIGHT", new Tuple<>(1, 0));
        directions.put("UPLEFT", new Tuple<>(-1, 1));
        directions.put("UPRIGHT", new Tuple<>(1, 1));
        directions.put("DOWNLEFT", new Tuple<>(-1, -1));
        directions.put("DOWNRIGHT", new Tuple<>(1, -1));
    }

    public static Map<String, Tuple<Integer, Integer>> getDirections() {
        return Collections.unmodifiableMap(directions);
    }
}

public Collection<V> values() {
    Collection<V> vs = new ArrayList<>();
    for (Entry<K, V> e : entrySet()) {
        vs.add(e.getValue());
    }
    return vs;
}