Question

What is the difference between a checked and unchecked exception?

Answer 1

checked exception occur at compile time where as unchecked exception occur at runtime.

Answer 2

Checked exception
- Checked exceptions occur at compile time.
- The compiler checks a checked exception.
- These types of exceptions can be handled at the time of compilation.
Example - File Not Found Exception, No Such Field Exception

unchecked exception
- Unchecked exceptions occur at runtime.
- The compiler does not check these types of exceptions.
- These types of exceptions cannot be a catch or handled at the time of compilation because they get generated by the mistakes in the program.
Example - Empty stack exception, Arithmetic exception, null pointer exception.

Comments

This seems generally right, except that both kinds can be caught with a try/catch block.

A key difference is that "checked exceptions" must be handled (with try/catch, or by a "throws" declaration) or the compiler won't let your code compile.

It is up to you whether or not to handle any "unchecked" exceptions in your code.