java Y轴在代码中反转,应该形成一个矩形
所以我的代码由3个部分组成,2个类和测试思想是,2个类使用来自测试的输入形成一个矩形。 这是测试代码
@Test
public void testRectangle1() {
Point center = new Point(20, 30);
Rectangle rect = new Rectangle(center, 20, 20);
assertAll(
() -> assertEquals(10, rect.getTopLeft().getX()),
() -> assertEquals(20, rect.getTopLeft().getY()),
() -> assertEquals(30, rect.getBottomRight().getX()),
() -> assertEquals(40, rect.getBottomRight().getY()),
() -> assertEquals(20, rect.getWidth()),
() -> assertEquals(20, rect.getHeight())
);
}
第一节课叫Point,效果很好
public class Point {
private int x, y;
public Point(int x, int y) {
this.x = x;
this.y = y;
}
public Point() {
this(0, 0);
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public void moveTo(int newX, int newY) {
x = newX;
y = newY;
}
public void moveRel(int dx, int dy) {
x += dx;
y += dy;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + x;
result = prime * result + y;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Point other = (Point) obj;
if (x != other.x)
return false;
if (y != other.y)
return false;
return true;
}
}
所以这是第二类形成了纠结。它由几个传统的矩形构造方法组成
public class Rectangle {
public int width = 0;
public int height = 0;
public Point center;
public Rectangle(Point center, int width, int height) {
int x = 0;
int y = 0;
this.width=width;
this.height=height;
this.center=center;
}
public Point getTopLeft() {
Point point = new Point(center.getX(), center.getY());
point.moveRel(- width / 2, height / 2);
return point;
}
public Point getBottomRight() {
Point point = new Point(center.getX(), center.getY());
point.moveRel(width / 2, - height / 2);
return point;
}
public int getWidth() {
return width;
}
public int getHeight() {
return height;
}
}
所以问题是,y轴似乎在某种程度上是颠倒的,因为当我运行测试时,它返回了错误的值,
() -> assertEquals(20, rect.getTopLeft().getY())
,返回40而不是20,然后进行测试
() -> assertEquals(40, rect.getBottomRight().getY())
,返回2o而不是40。所以看起来左上角和右下角的点在y轴上是倒转的
# 1 楼答案
在moveRel中添加高度/2以获得左上角。因此,你得到40而不是20是正常的
在高度参数之前似乎存在符号错误: