| 【问题描述】先定义Point类，再定义Triangle类，在Triangle类中定义三个Point对象来表示一个三角形的三个顶点，然后定义一个方法isTri()对这三个点是否能构成三角形进行判定。构造方法先调用isTri()，如果三个点能够构成三角形，则对三角形对象进行初始化，否则给出提示并退出程序。最后定义两个方法getPerimeter()和getArea()，分别求三角形的周长和面积。
在TestTriangle类的main()方法中创建一个Triangle对象，从键盘输入该对象三个顶点的坐标，然后求该三角形的周长和面积（小数点后保留3位），或者给出不能构成三角形的提示。
【样例输入1】
1 1
2 2
3 3
【样例输出1】
Please enter the coordinates of p1:
1 1
Please enter the coordinates of p2:
2 2
Please enter the coordinates of p3:
3 3
Can't form a triangle!
【样例输入2】
1 1
2 0
0 3
【样例输出2】
Please enter the coordinates of p1:
1 1
Please enter the coordinates of p2:
2 0
Please enter the coordinates of p3:
0 3
Perimeter=7.256
Area=0.500 |
import java.util.Scanner;
class Point {
private double x, y;
public Point(double x, double y) {
super();
this.x = x;
this.y = y;
}
public double getX() {
return x;
}
public void setX(double x) {
this.x = x;
}
public double getY() {
return y;
}
public void setY(double y) {
this.y = y;
}
public double getDisstance(Point p) {
double dist = Math.sqrt((this.getX() - p.getX()) * (this.getX() - p.getX())
+ (this.getY() - p.getY()) * (this.getY() - p.getY()));
return dist;
}
}
class Triangle {
Point a;
Point b;
Point c;
public Triangle(Point a, Point b, Point c) {
super();
this.a = a;
this.b = b;
this.c = c;
}
public boolean isTri() {
double m, n, z;
m = a.getDisstance(b);
n = b.getDisstance(c);
z = c.getDisstance(a);
if ((m + n) > z && (m + z) > n && (n + z) > m) {
return true;
} else
return false;
}
public Point getA() {
return a;
}
public void setA(Point a) {
this.a = a;
}
public Point getB() {
return b;
}
public void setB(Point b) {
this.b = b;
}
public Point getC() {
return c;
}
public void setC(Point c) {
this.c = c;
}
public double getPerimeter() {
double m, n, z;
m = a.getDisstance(b);
n = b.getDisstance(c);
z = c.getDisstance(a);
return m + n + z;
}
public double getArea() {
double m, n, z, half;
m = a.getDisstance(b);
n = b.getDisstance(c);
z = c.getDisstance(a);
half = (m + n + z) / 2;
return Math.sqrt(half * (half - m) * (half - n) * (half - z));
}
}
public class TestTriangle {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.printf("Please enter the coordinates of p1:\n");
double ax = sc.nextDouble();
double ay = sc.nextDouble();
Point a = new Point(ax, ay);
System.out.printf("Please enter the coordinates of p2:\n");
double bx = sc.nextDouble();
double by = sc.nextDouble();
Point b = new Point(bx, by);
System.out.printf("Please enter the coordinates of p3:\n");
double cx = sc.nextDouble();
double cy = sc.nextDouble();
Point c = new Point(cx, cy);
sc.close();
Triangle d = new Triangle(a, b, c);
if (d.isTri() == true) {
double d2 = d.getArea();
double d1 = d.getPerimeter();
System.out.printf("Perimeter=%.3f\n", d1);
System.out.printf("Area=%.3f\n", d2);
} else {
System.out.printf("Can't form a triangle!\n");
System.exit(0);
}
}
}
