Checked Exceptions

Any exception that is a subclass of Exception (or Exception itself), except for RuntimeException and it’s subclasses, is a checked exception.

The Java compiler forces you to catch checked exceptions (and either swallow or re-throw).

Some common examples of checked exceptions are:

  • IOException 
  • FileNotFoundException 
  • ClassNotFoundException 
  • InvocationTargetException 
  • SQLException 
  • DataAccessException 


The exception can be thrown while trying to remove an element from a Collection (e.g. an ArrayList) while iterating over it using a standard for loop.

Another way a ConcurrentModificationException can be thrown is if you forget to copy a Collection and rather take a reference to it, and then try and access the Collection.

For example, the following line won’t actually copy the entire list: