教会我如何在Java中重载方法的练习程序不断输出错误答案

Question

I understand the concept of overloading and I'd like to think I have done it succesfully in this program; it runs fine but the output is not correct.

The program is supposed to calculate the area of a circle from two points, one being the radius and the other being a random point on the outside of the circle. The two points are given by the user, and each point consists of two numbers. So point one is x1, x2, while point two is y1, y2.

I did a test run by inputting the numbers 1, 2, 3, and 4, which should give me an answer of 3.1458....(pi). However, it gives me 25.132741228718352.

Any help on figuring out what is giving me this weird output would be much appreciated.

Here is the code import java.util.Scanner; public class AreaCircle {

static Scanner input  = new Scanner(System.in);

public static double getDistance(double x1, double y1,
                            double x2, double y2) {

    double dx = x2 - x1;
    double dy = y2 - y1;

    double distanceSquared = dx * dx + dy * dy;
    double radius = Math.sqrt(distanceSquared);
    return radius;
}

public static double areaCircle (double radius){
double area = (double)Math.PI * (radius * radius);
return area;
}

public static double areaCircle (double x1, double x2,
                                    double y1, double y2) {
    double radius = getDistance(x1, x2, y1, y2);

    double area = areaCircle (radius);

    return area;

}
public static void main(String[] args) {
System.out.print("Please input two points, with the first being \n"
        + "the middle of the circle and the other being \n"
        + "a point on the outside of the circle. These two points will \n"
        + "be used to find the area of your circle. \n\n"
        + "Input the first point here: ");
double x1 = input.nextDouble();
System.out.print("Input the second point here: ");
double x2 = input.nextDouble();
System.out.print("Input the third point here: ");
double y1 = input.nextDouble();
System.out.print("Input the fourth point here: ");
double y2 = input.nextDouble();
double result = areaCircle(x1, x2, y1, y2);
System.out.println("Your result is: " + result);
}

}

Answer 1

You're actually calculating the distance between (1, 2) and (3,4), since you've switched x2 with y1 in distance (compare it with the area function -- you'll see what I mean).

The distance between (1,2) and (3,4) is sqrt 8, when you substitute that into the formula, it gives an area of 8 * pi ~= 25.