java/w4/Triangle.java

package com.shape;

public class Triangle extends Shape {
    private double sideA;
    private double sideB;
    private double sideC;

    public Triangle(double sideA, double sideB, double sideC) {
        if (!isValidTriangle(sideA, sideB, sideC)) {
            throw new IllegalArgumentException("输入的三边无法构成三角形（必须满足三角形不等式）");
        }
        this.sideA = sideA;
        this.sideB = sideB;
        this.sideC = sideC;
    }

    // 判断是否能构成三角形（三角形不等式）
    private boolean isValidTriangle(double a, double b, double c) {
        return (a + b > c) && (a + c > b) && (b + c > a) && a > 0 && b > 0 && c > 0;
    }

    @Override
    public double getArea() {
        // 使用海伦公式计算三角形面积
        double p = (sideA + sideB + sideC) / 2;   // 半周长
        return Math.sqrt(p * (p - sideA) * (p - sideB) * (p - sideC));
    }
}