Unhandled Exception Type in JAVA

Question

I have a two classes in the same package in JAVA.

One class in which I have a constructor an exception I tried to create myself:

public class ZooException extends Exception {

        public ZooException(String error) {
            super(error);
        }   
}

Another class needs to call this exception at one point:

public class Zoo<T extends Animal>

Zoo(int capacity) {
        if (capacity <= 1) {
        throw new ZooException("Zoo capacity must be larger than zero");
    }
}

I notice two things here

1. In the ZooException class, I get a warning: "The serializable class CageException does not declare a static final serialVersionUID field of type long"
2. In the Zoo class, on the line that starts with "throw new", I get a compile error: "Unhandled exception type CageException"

Any ideas on what I can do to solve this error in the Zoo class? Thank you in advance!

Answer 1

You are extending Exception, a checked exception, this means that any method which throws that exception needs to say so:

Zoo(int capacity) throws ZooException {

And any code calling that constructor will have to try {} catch {} or throw it again.

If you don't want it to be checked, use extends RuntimeException instead

Answer 2

About unchecked exceptions @Will P is right.

About serialVersionUID, this means - since Exception is Serializable - if you anytime decide that a previous version of your class should be incompatible with your newer version ( usually for public APIs), for example, that class had undergone major changes, simply change the unique id, and reading an object of the old version would throw an exception.

Answer 3

Zoo(int capacity) throws ZooException {
    if (capacity <= 1) {
    throw new ZooException("Zoo capacity must be larger than zero");
}

You must declare checked exceptions or handle them with a try-catch bock. Try reading up on exceptions: http://docs.oracle.com/javase/tutorial/essential/exceptions/