这个符合你的要求：import java.io.*; class MyException extends Exception{ String s="不能以负数作为边长"; public String toString(){ return s; } }public class isTriangle { boolean triangle (int a,int b,int c){ boolean flag; if(a*a==b*b+c*c||b*b==c*c+a*a||c*c==a*a+b*b) flag=true; else flag=false; return flag; } public static void main(String[] args)throws IOException,MyException { isTriangle it=new isTriangle(); int [] num=new int[3]; String [] string=new String[3]; boolean b; for(int i=0;i<3;i++) { System.out.println("请输入第"+(i+1)+"个数："); BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); string[i]=br.readLine(); num[i]=Integer.parseInt(string[i]); } if(num[0]<=0||num[1]<=0||num[2]<=0) try{ throw new MyException(); } catch(MyException e) { System.out.println(e.toString()); } else if((num[0]+num[1])<=num[2]||(num[2]+num[1])<=num[0]||(num[0]+num[2])<=num[1]) System.out.print("不能构成三角形！"); else { b=it.triangle(num[0],num[1],num[2]); System.out.println(b); } }}