java - 点类坐标

Question

我有一个作业是这样解释的:

Write a definition of a class named Point that might be used to store and manipulate the location of a point on the plane. The point is stored as two coordinates: x and y. You will need to declare and implement the following methods:

1. Two constructors:a. no-argument constructor that sets the point coordinates to (0,0), andb. a constructor that takes x and y coordinate of the point and sets membervariables.
2. Method set that sets the private data after an object of this class is created.
3. A method to move the point by an amount along the vertical and horizontal directions specified by the first and second arguments: move(double dx, double dy)
4. The method to rotate the point by 90 degrees clockwise around the origin. Hint: when point is getting rotated 90 clockwise around the origin the following changes happen to its coordinates: xrotated = y; yrotated = -x .
5. two accessor methods to retrieve the coordinates of the point.

这应该是两个不同的调用。这些项目在第二个(不是主类)我将在主课上调用它。 (我就是这么做的)。

这是我的代码，但我不明白下一步应该做什么。

private double x;    
private double y;    


public Point(double initialX, double initialY) {
    x = initialX;
    y = initialY;
}


public Point() {
    x = 0;
    y = 0;
}


public double getX() {
    return x;
}


public double getY() {
    return y;
}


public void move(double dx, double dy) {
    x += dx;
    y += dy;   
}

Answer 1

你几乎拥有了一切，干得好。对于旋转 90 度函数，您已经获得了关于要做什么的很好的线索。假设您有一个点 (1,2)，然后旋转它。你最终会得到(2,-1)。如果你再次旋转它，你会得到(-1，-2)。再次旋转得到 (-2,1)，第四次 90 度旋转得到 (1,2)，这就是你开始时的结果。想出一个可以做到这一点的函数。它不应超过 3 行。

设置函数(用于设置或更改值的函数)只是可用于设置点的值的函数。因此，您将有一个函数“setX(...) { ... }”和一个函数“setY(...) { ... }”。这些应该非常简单。

如果您仍然感到困惑，请随时提出进一步的问题。