Exception hierarchy

Throwable acts as a root for exception hierarchy.

The throwable class contains the following two child classes. 

Exception: Most of the cases exceptions are caused by our program and these are recoverable.

Error: Most of the cases errors are not caused by our program these are due to lack of system

resources and these are non-recoverable.

Checked Vs Unchecked Exceptions:

• The exceptions which are checked by the compiler for smooth execution of the program at runtime are called checked exceptions.

          1) HallTicketMissingException

          2) PenNotWorkingException

          3) FileNotFoundException

• The exceptions which are not checked by the compiler are called unchecked exceptions.

          1) BombBlaustException

          2) ArithmeticException

          3) NullPointerException

Note: RuntimeException and its child classes, Error, and its child classes are unchecked and all the remaining are considered as checked exceptions.

Note: Whether exception is checked or unchecked compulsory it should occur at runtime only there is no chance of occurring any exception at compile time.

Partially checked Vs fully checked:

• A checked exception is said to be fully checked if and only if all its child classes are also checked.

Example:

          1) IOException

          2) InterruptedException

• A checked exception is said to be partially checked if and only if some of its child classes are unchecked.

Example: Exception

• The only partially checked exceptions available in java are:

          1. Throwable.

          2. Exception.

Which of the following are checked?

   1. RuntimeException-----unchecked

   2. Error-----unchecked

   3. IOException-----fully checked

   4. Exception-----partially checked

   5. InterruptedException-----fully checked

   6. Throwable------partially checked

Diagram: