用JAVA编写一个代表三角形的类，其中3条边为三角形的属性，并封装有求三角形的面积和周长的方法。分别利用3条边为3、4、5、和7、8、9的两个三角形进行测试

public class Triangle {
    private double side1;
    private double side2;
    private double side3;

    public Triangle(double side1, double side2, double side3) {
        this.side1 = side1;
        this.side2 = side2;
        this.side3 = side3;
    }

    public double getSide1() {
        return side1;
    }

    public double getSide2() {
        return side2;
    }

    public double getSide3() {
        return side3;
    }

    public double getArea() {
        double p = (side1 + side2 + side3) / 2;
        return Math.sqrt(p * (p - side1) * (p - side2) * (p - side3));
    }

    public double getPerimeter() {
        return side1 + side2 + side3;
    }

    public static void main(String[] args) {
        Triangle triangle1 = new Triangle(3, 4, 5);
        System.out.println("Triangle 1: Side 1 = " + triangle1.getSide1() +
                ", Side 2 = " + triangle1.getSide2() +
                ", Side 3 = " + triangle1.getSide3() +
                ", Area = " + triangle1.getArea() +
                ", Perimeter = " + triangle1.getPerimeter());

        Triangle triangle2 = new Triangle(7, 8, 9);
        System.out.println("Triangle 2: Side 1 = " + triangle2.getSide1() +
                ", Side 2 = " + triangle2.getSide2() +
                ", Side 3 = " + triangle2.getSide3() +
                ", Area = " + triangle2.getArea() +
                ", Perimeter = " + triangle2.getPerimeter());
    }
}

输出：

Triangle 1: Side 1 = 3.0, Side 2 = 4.0, Side 3 = 5.0, Area = 6.0, Perimeter = 12.0
Triangle 2: Side 1 = 7.0, Side 2 = 8.0, Side 3 = 9.0, Area = 26.832815729997478, Perimeter = 24.0