Best practice for validating values provided to a constructor?

Question

Context: I am writing a semaphore class for school, and one of the requirements is that it may not be initialized with a negative value.

Right now my constructor throws an exception:

/**
 * Constructor
 */
public Semaphore(int value) throws Exception
{   
    if (value < 0)
        throw new Exception("Negative value provided for initial constructor.");
    this.value = value;
}

Handling an exception in order to instantiate a semaphore seems overly heavy to me, so I am considering quietly setting any negative values to zero, ie:

/**
 * Constructor
 */
public Semaphore(int value) 
{   
    if (value < 0)
        this.value = 0;
    else
        this.value = value;
}

Answer 1

You should use the IllegalArgumentException instead. It requires no explicit exception handling and it behaves exactly like you want, that is to signal an illegal argument.

Answer 2

If you say: Hey, the values are directly from the user. Correct them with a message.

If you say: Hey, the values are generated and a bug produced a negative value.

throw new IllegalArgumentException("Negative Value",
    new IndexOutOfBoundsException(value+""));

If you say: Hey, i like to let the VM decide to throw or correct. Use assert value > 0;.