Java 練習(14)：判斷是否為正三角形，並拋出自訂例外

Java 7 教學手冊第五版 第十三章習題

12.三角形的三個邊為 a、b、c，請判斷是否為正三角形，並利用try-catch捕捉自訂的例外，這些例外由 triangle()拋出。

public class App13_12
{
 

 public static void main(String[] args)
 {

  try
  {
   Triangle t = new Triangle();
   t.triangle(5, 2, 2);
  } catch (NotTriangle e)
  {
   System.out.println(e.getMessage());
  } catch (EquilateralTriangle e)
  {
   System.out.println(e.getMessage());
  } catch (NotEquilateralTriangle e)
  {
   System.out.println(e.getMessage());
  }

 }
}

class NotTriangle extends Exception
{

 public NotTriangle(int a, int b, int c)
 {
  super("不構成三角形");
 }
}

class EquilateralTriangle extends Exception
{

 public EquilateralTriangle(int a, int b, int c)
 {
  super("這是正三角形");
 }
}

class NotEquilateralTriangle extends Exception
{

 public NotEquilateralTriangle(int a, int b, int c)
 {
  super("這不是正三角形");
 }
}

class Triangle
{

 public void triangle(int a, int b, int c) throws NotTriangle, EquilateralTriangle, NotEquilateralTriangle
 {

  if ((a + b) < c || (a + c) < b || (b + c) < a)
  {
   throw new NotTriangle(a, b, c);
  } else if (a == b && b == c && c == a)
  {
   throw new EquilateralTriangle(a, b, c);
  } else
  {
   throw new NotEquilateralTriangle(a, b, c);
  }
 }
}