Question

i have this in a class:

/* parses a Value out of a String */
public static int parseValue(final String text) throws NumberFormatException {

    String cleanedValue = text.replace("-", "").replace(",", ".");
    return Math.round(Float.parseFloat(cleanedValue) * 100);
}

For some reason javac doesn’t complain that i don’t catch the NumberFormatException in the calling code.

Can someone tell me why that is?

Answer 1

From the Java Docs, NumberFormatException is,

Thrown to indicate that the
application has attempted to convert a
string to one of the numeric types,
but that the string does not have the
appropriate format.

Just look at the inheritance structure, NumberFormatException derives from RuntimeException, which the compiler doesn’t force to catch those exceptions. It’s not recommended. You need to catch/declare only checked exceptions.

java.lang.Object  
   java.lang.Throwable  
      java.lang.Exception
          java.lang.RuntimeException
              java.lang.IllegalArgumentException
                  java.lang.NumberFormatException 

Now, a method is not required to declare in its throws clause any subclasses of RuntimeException that might be thrown during the execution of the method but not caught.