Question

I’m trying to learn more about basic Java and the different types of Throwables, can someone let me know the differences between Exceptions and Errors?

Answer 1

Errors should not be caught or handled (except in the rarest of cases). Exceptions are the bread and butter of exception handling. The Javadoc explains it well:

An Error is a subclass of Throwable that indicates serious problems that a
reasonable application should not try to catch. Most such errors are abnormal
conditions.

Look at a few of the subclasses of Error, taking some of their JavaDoc comments:

• AnnotationFormatError – Thrown when the annotation parser attempts to read an annotation from a class file and determines that the annotation is malformed.
• AssertionError – Thrown to indicate that an assertion has failed.
• LinkageError – Subclasses of LinkageError indicate that a class has some dependency on another class; however, the latter class has incompatibly changed after the compilation of the former class.
• VirtualMachineError – Thrown to indicate that the Java Virtual Machine is broken or has run out of resources necessary for it to continue operating.

There are really three important subcategories of Throwable:

• Error – Something severe enough has gone wrong the most applications should crash rather than try to handle the problem,
• Unchecked Exception (aka RuntimeException) – Very often a programming error such as a NullPointerException or an illegal argument. Applications can sometimes handle or recover from this Throwable category — or at least catch it at the Thread’s run() method, log the complaint, and continue running.
• Checked Exception (aka Everything else) – Applications are expected to be able to catch and meaningfully do something with the rest, such as FileNotFoundException and TimeoutException…