1.题目：

2.代码：

public class Xain{            //定义类名，要与文件.class名字一样private double yibian;     //封装private double erbian;private double sanbian;public Xain(double yibian,double erbian,double sanbian){  //初始化变量this.yibian=yibian;this.erbian=erbian;this.sanbian=sanbian;}public double SJXZC(){          //定义类方法return yibian + erbian +sanbian;}public double SSS(){          //定义类方法double s = SJXZC() / 2; // 半周长double area = Math.sqrt(s * (s - yibian) * (s - erbian) * (s - sanbian));return area;}public static void main(String[] args){Xain SJX = new Xain(3,4,5);   //调用类double area= SJX.SSS();                          //调用类方法   对象.类方法System.out.println(area);double zc =  SJX.SJXZC();System.out.println(zc);}}

3.收获：

a.海伦公式

b.当无法解决报错问题时，交给GPT

c.定义类方法要用括号