public class Triangle {
int a,b,c //三条边
double S//面积
boolean isTri = true
Triangle(){
a=3 b=4 c=5
}
Triangle(int bian){
a=b=c=bian
}
Triangle(int bian1,int bian2,int bian3){
if(bian1 + bian2 > bian3 && bian1 + bian3 > bian2 && bian2 + bian3 > bian1){
a = bian1b=bian2c=bian3
}else{
isTri = false
System.out.print("不是三角形")
}
}
private double getS(){
if(isTri){
int s = (a+b+c)/2
double ss = Math.sqrt(s * (s - a) * (s - b) * (s - c))
BigDecimal b = new BigDecimal(ss)
return b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue()
}
return 0
}
public static void main(String[] aa){
System.out.println(new Triangle().getS())
System.out.println(new Triangle(5).getS())
System.out.println(new Triangle(5,8,6).getS())
System.out.println(new Triangle(2,9,6).getS())
}
}
代码如下，主要知识点三角形面积公式：p=(a+b+c)/2,s^2=p*(p-a)*(p-b)*(p-c)JDK中的开方方法：Math.sqrt()public class Demo {public static void main(String[] args) {double a=3 double b=4 double c=5 double p=(a+b+c)/2 System.out.println(Math.sqrt(p*(p-a)*(p-b)*(p-c))) }}
