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

In the ZooException class, I get a warning: "The serializable class CageException does not declare a static final serialVersionUID field of type long"
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!

Using eclipse? Left of the code, click on the error symbol and eclipse will suggest some fixes for you. If you select one, it will even do it for you. — jlordo, Jun 02 '13 at 17:30

score 11 · Accepted Answer · answered Jun 02 '13 at 17:25

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

score 1 · Answer 2 · answered Jun 03 '13 at 02:58

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.

score 0 · Answer 3 · answered Jun 02 '13 at 17:25

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/

Unhandled Exception Type in JAVA

3 Answers3