Java Exception as checked Exception but not required to be thrown in trycatch

Question

I have this snippet.

public final class StackOverflow{
   class MyException extends Throwable{
   }
   private void a(){
       try{
       }catch(MyExceptio         


        

Answer 1

It is explained in the Java Language Specification (emphasis in bold):

It is a compile-time error if a catch clause can catch checked exception class E1 and it is not the case that the try block corresponding to the catch clause can throw a checked exception class that is a subclass or superclass of E1, unless E1 is Exception or a superclass of Exception.

I guess the rationale behind this is that: MyException is indeed a checked exception. However, unchecked exceptions also extend Exception (transitive inheritance from RuntimeException), so having a catch include the Exception class is excluded from the exception analysis done by the compiler.

Answer 2

Exception extends from RuntimeException will considered as uncheched exception, so it's ok:

class MyException extends RuntimeException { }

try {
    ...
} catch (MyException e) {

}

Your exception extends from Throwable, so it is cheched exception. Since the compiler noticed that it is never thrown, so the compile fails.