修改代码，使代码正常运行：public interface triangle { double getPerimeter(double a, double b, double c); double getArea(double a, double b, double c); } class Perimeter implements triangle { public double getPerimeter(double a,double b,double c) { double perimeter = 0; perimeter = (a+b+c); return perimeter; } } class Area implements triangle { public double getArea(double a,double b,double c) { double area = 0; double p = 0; p = (a+b+c)/2; area = Math.sqrt(p*(p-a)*(p-b)*(p-c)); return area; } } public class Output { public static void main(String[] args) { double a = 3, b = 4, c = 5; Perimeter C = new Perimeter(); Area S = new Area(); System.out.println("三角形的周长为："+C); System.out.println("三角形的面积为："+S); } }

修改后的代码如下：

public interface Triangle {
    double getPerimeter(double a, double b, double c);
    double getArea(double a, double b, double c);
}

class Perimeter implements Triangle {
    public double getPerimeter(double a, double b, double c) {
        double perimeter = 0;
        perimeter = (a + b + c);
        return perimeter;
    }
}

class Area implements Triangle {
    public double getArea(double a, double b, double c) {
        double area = 0;
        double p = 0;
        p = (a + b + c) / 2;
        area = Math.sqrt(p * (p - a) * (p - b) * (p - c));
        return area;
    }
}

public class Output {
    public static void main(String[] args) {
        double a = 3, b = 4, c = 5;
        Perimeter c = new Perimeter();
        Area s = new Area();
        System.out.println("三角形的周长为：" + c.getPerimeter(a, b, c));
        System.out.println("三角形的面积为：" + s.getArea(a, b, c));
    }
}

主要修改如下：

1. 将 `triangle` 修改为 `Triangle`，符合 Java 命名规范；

2. 将 `Perimeter C` 和 `Area S` 修改为 `Perimeter c` 和 `Area s`，符合 Java 命名规范；

3. 在 `main` 方法中，将 `System.out.println` 中的 `C` 和 `S` 改为 `c.getPerimeter(a, b, c)` 和 `s.getArea(a, b, c)`，以调用 `Perimeter` 和 `Area` 类中的方法，获取计算结果。