求接口源码

interface Shape {
double getArea();
double getCircumsta();
}
class Triangle implements Shape {
private double sideA;
private double sideB;
private double sideC;
private boolean flage;
Triangle(double a, double b, double c) {
    this.sideA = a;
    this.sideB = b;
    this.sideC = c;
    if ((a + b > c && a - b < c) || (a - c > b && a + c > b)
            || (b + c > a && b - c < a)) {
        this.flage = true;
    } else {
        this.flage = false;
    }
}
public double getArea() {
    if (flage) {
        double s = sideA + sideB + sideC;
        return Math.sqrt(s * (s - sideA) * (s - sideB) * (s - sideC));

    } else {
        System.out.println("不能构成三角形");
        return 0.0;
    }

}
public double getCircumsta() {
    if (flage) {

        return sideA + sideB + sideC;
    }

    else {
        System.out.println("不能构成三角形");

        return 0.0;
    }
}
}

class RecTangle implements Shape {
private double sideA;
private double sideB;
RecTangle(double a, double b) {
    this.sideA = a;
    this.sideB = b;
}

public double getArea() {//实现接口方法

    return sideA * sideB;
}

public double getCircumsta() {//实现接口方法
    return 2 * (sideA + sideB);
}
}

public class T1 {
public static void main(String[] args) {
Scanner myInput = new Scanner(System.in);

    System.out.println("请输入需要计算的三角形的三边长：");
    System.out.println("第一边：");
    double a = myInput.nextDouble();
    System.out.println("第二边：");
    double b = myInput.nextDouble();
    System.out.println("第三边：");
    double c = myInput.nextDouble();

    Triangle myTri = new Triangle(a, b, c);//创建一个三角形对象

    System.out.println("请输入需要计算的长方形的边长：");
    System.out.println("长：");
    double length = myInput.nextDouble();
    System.out.println("宽：");
    double wide = myInput.nextDouble();

    RecTangle myRec = new RecTangle(length,wide);//创建一个长方形对象
    System.out.println("三角形周长：" + myTri.getCircumsta());
    System.out.println("三角形面积：" + myTri.getArea());

    System.out.println("长方形周长：" + myRec.getCircumsta());
    System.out.println("长方形面积：" + myRec.getArea());

    myInput.close();//资源回收
}
}