How should I throw a divide by zero exception in Java without actually dividing by zero?

Question

I have an I2C device that wants two inputs: a denominator and a numerator. Both are written to separate addresses, so no actual calculation (numerator/denominator

Answer 1

Do this:

if (denominator == 0) throw new ArithmeticException("denominator == 0");

ArithmeticException is the exception which is normally thrown when you divide by 0.

Answer 2

You should not throw an ArithmeticException. Since the error is in the supplied arguments, throw an IllegalArgumentException. As the documentation says:

Thrown to indicate that a method has been passed an illegal or inappropriate argument.

Which is exactly what is going on here.

if (divisor == 0) {
    throw new IllegalArgumentException("Argument 'divisor' is 0");
}

Answer 3

There are two ways you could do this. Either create your own custom exception class to represent a divide by zero error or throw the same type of exception the java runtime would throw in this situation.

Define custom exception

public class DivideByZeroException() extends ArithmeticException {
}

Then in your code you would check for a divide by zero and throw this exception:

if (divisor == 0) throw new DivideByZeroException();

Throw ArithmeticException

Add to your code the check for a divide by zero and throw an arithmetic exception:

if (divisor == 0) throw new java.lang.ArithmeticException("/ by zero");

Additionally, you could consider throwing an illegal argument exception since a divisor of zero is an incorrect argument to pass to your setKp() method:

if (divisor == 0) throw new java.lang.IllegalArgumentException("divisor == 0");

Answer 4

Something like:

if(divisor == 0) {
  throw new ArithmeticException("Division by zero!");
}

Answer 5

public class ZeroDivisionException extends ArithmeticException {
    // ...
}

if (denominator == 0) {
    throw new ZeroDivisionException();
}