CODEWITHSUNDEEP
javaexception
noobprogrammer
noobprogrammer

Reputation: 523

Testing a java class

What is the problem here? I am just simply trying to catch a custom exception depending on a if statement in my constructor, the entire code

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package question3_test;

/**
 *
 * @author jackandjill
 */
public class Triangle2 
{
    private int side1, side2, side3;
    private  double area;
    private  String message;    

    public  int getSide1()
    {
        return side1;
    }

    public void setSide1(int s1)
    {
        side1 = s1;
    }

    public  int getSide2()
    {
        return side2;
    }

    public void setSide2(int s2)
    {
        side2 = s2;
    }

    public  int getSide3()
    {
        return side3;
    }

    public void setSide3(int s3)
    {
        side3 = s3;
    }

   public Triangle2(int a,int b,int c) throws InvalidValueException
   {
    setSide1(a);
    setSide2(b);
    setSide3(c);

    try
    {
         if (!(side1 + side2 > side3) && (side2 + side3 > side1)&& (side1 + side3 > side2))

                 throw new InvalidValueException("Invalid Value");
    }
    catch (InvalidValueException excep)
    {
        message = excep.getMessage();
        //throw new InvalidValueException(message);
    }

    public double findArea(int side_1, int side_2, int side_3)
    {
        int s, a, b,c;
        a = side_1;
        b = side_2;
        c = side_3;
        s = ((a + b + c)/2);
        area = Math.sqrt(s*(s-a)*(s-b)*(s-c));
        //area =
        return area;
    }
   }
}

The problem is at my catch statement, it is underlined in red and says never thrown in the corresponding try statement

Upvotes: 1

Views: 319

Answers (4)

Rohit Jain
Rohit Jain

Reputation: 213223

You can't throw an Exception class like in the below code: -

throw InvalidValueException;

You have to make a new instance of your exception, and then throw it: -

throw new InvalidValueException();

But, still there is some logic problem in your code. You have declared your Exception to be throws, but at the same time, you are handling it in the catch block itself. Why would you do that?

UPDATE: -

As per your modified post: -

try
{
   if (!(side1 + side2 > side3) && (side2 + side3 > side1) && 
        (side1 + side3 > side2))

       message = "Invalid Triangle";

} catch (InvalidValueException e) {
    message = "Invalid Traingle";
}

Since you are no-where throwing any Exception in your try block, the catch block will complain about that..

If you want to throw an exception and catch it in place, use it like this: -

public Triangle2(int a,int b,int c) throws InvalidValueException

      if (!(side1 + side2 > side3) && (side2 + side3 > side1) && 
            (side1 + side3 > side2))

           throw new InvalidValueException("Invalid Value")
}

And suppose you are using it from your main method, you should have a try-catch block there, to handle the declared exception in constructor.: -

public static void main(String[] args) {
    Triangle triangle = null;
    try {
         triangle = new Triangle(2, 3, 4);
    } catch (InvalidValueException e) {
        e.printStackTrace();
    }
}

If you handle the exception in your method only, you should not declare it in your method declaration.. But if you are not handling it, then you must declare that exception to be thrown.

An exception should be either handled, or declared to be thrown (In which case, you should actually throw that exception), but never both

See This tutorial for more about Exception: - http://docs.oracle.com/javase/tutorial/essential/exceptions/catchOrDeclare.html

Upvotes: 2

Bhesh Gurung
Bhesh Gurung

Reputation: 51030

Looks like InvalidValueException is a checked exception (compiletime exception) and your code within the catch block doesn't throw that exception.

You can overcome that error message (in a meaningful way) by first checking the values in your method and immediately throwing the exception if any of them are not valid.

Or, if possible, you can also make it a RuntimeException instead.

Upvotes: 0

Marko Topolnik
Marko Topolnik

Reputation: 200148

There is some confusion in your code in the way you use exceptions.

  1. Inside the try block you never throw your exception, but try to catch it below.
  2. You declare that your method throws the exception, but the method's body never throws it.
public Triangle2(int a,int b,int c) 
throws InvalidValueException // declared, but never thrown!
{
  try
  {
    if (!(side1 + side2 > side3) && (side2 + side3 > side1)&& (side1 + side3 > side2))
      message = "Invalid Triangle";
  }
  catch (InvalidValueException excep)  // caaught, but never thrown in try body!
  {
    message = "Invalid Triangle";
  }
}

This is the way you should write it, much simpler in fact:

public Triangle2(int a,int b,int c) throws InvalidValueException
{
  setSide1(a);
  setSide2(b);
  setSide3(c);
  if (!(side1 + side2 > side3) && (side2 + side3 > side1)&& (side1 + side3 > side2))
    throw new InvalidValueException("Invalid Triangle");
}

You are not supposed to catch the exception in the same context where you threw it: the place where you use the constructor, new Triangle2(a,b,c), is the (earliest sensible) place to catch.

Upvotes: 2

Subhrajyoti Majumder
Subhrajyoti Majumder

Reputation: 41200

You should re-throw your custom exception from catch block .

catch (InvalidValueException excep)
{
    message = "Invalid Triangle";
    throw new InvalidValueException(message);
}

Upvotes: 0

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