Question

我正在尝试编写一个java项目。我在Slope方法有问题！我正在使用我们的讲师给出的测试人员来运行和测试我的代码。当我运行程序时，结果显示预期输出为1.5，但我得到-1.5。我无法弄清楚我做错了什么。提前谢谢！

//Segment.java
public class Segment implements SegmentInterface {
    // two Points that hold endpoints of the segment
    private Point p1;
    private Point p2;

    // Default constructor that will set the endpoints to new
    // Points with values (0,0) and (4,4)
    public Segment() {
        //this(0, 0, 4, 4);
        this.p1 = new Point(0, 0);
        this.p2 = new Point(4, 4);
    }

    // Parameterized constructor that accepts (int x1, int y1, int x2, int y2)
    // and creates and sets the endpoints
    public Segment(int x1, int y1, int x2, int y2) {

        //this.p1 = new Point(x1, y1);
        //this.p2 = new Point(x2, y2);

        if(x1 == x2 && y1 == y2){
            throw new IllegalArgumentException("Points can't have a lenght of 0!");
        } 

        else{
            this.p1 = new Point(x1, y1);
            this.p2 = new Point(x2, y2);
    }
}

     //A parameterized constructor that accepts (Point p1, Point p2) and sets both
     //the endpoints to a deep copy of the Points that are passed in.
     //Make sure to check to see if both Points are equal.  This would be a
     //theoretical "Segment" of length 0 which is not allowed, so throw a new
     //IllegalArgumentException.
    public Segment(Point p1, Point p2) {

        this.p1 = new Point(p1.getX(), p1.getY());
        this.p2 = new Point(p2.getX(), p2.getY());

            if(p1.equals(p2)){
                throw new IllegalArgumentException("Points cannot have same values!");
            } 
}

    // Copy constructor that accepts a Segment and initializes the data (of the
    // new Segment being created) to be the same as the Segment that was
    // received.
    public Segment(Segment other) {

        this(other.p1, other.p2);

        //if(other.p1 == other.p2){
            //throw new IllegalArgumentException("Undefine!");
        //}

}

/*
         * The slope method returns the slope of the Segment as a double.   If the segment
         * is vertical, the slope is undefined.  In that case, Java will return
         * Double.POSITIVE_INFINITY or Double.NEGATIVE_INFINITY, depending on which way you
         * subtract to calculate the slope.   You can either check for division by zero or
         * let Java do the calculation.  However, your requirements are to ALWAYS return
         * Double.POSITIVE_INFINITY if the slope is undefined.
         *
         * Also, strangely enough, Java may return 0 or -0 for a slope which is horizontal.
         * Your requirements are to always return a slope of 0 for a horizontal line
         * (don’t always just return the Java calculation).
         */
    public double slope() {

        if(p1.getY() == p2.getY()){
            return 0;
        }
            else if(p1.getX() == p2.getX()){
                double inf = Double.POSITIVE_INFINITY;
            return inf;
            }

            else{

            return ((double) (p2.getY() - p1.getY())
                    / (p1.getX() - p2.getX()));
        }

    }

这是我代码的一部分！

Answer 1

就在这里：

return ((double) (p2.getY() - p1.getY())
                / (p1.getX() - p2.getX()));

应该是

return ((double) (p2.getY() - p1.getY())
                / (p2.getX())-p1.getX() );

由于斜率公式表示m =（y2-y1）/（x2-x1）

为什么我的java斜率方法会出现负号？

1 个答案: