Java – Exception Hierarchy

February 10, 2017 SJ Exception Handling 0

In this article, we will discuss exception hierarchy in detail with figure and explanation

Exception Hierarchy:

Throwable class is the root class for every exception and it branches out to 2 main categories i.e.;

Exception
Error

1. java.lang.Throwable:

Throwable is the root class for exception & it’s sub-type and error & it’s sub-types
In other words, it is super class for exception & error
java.lang.Throwable class extends java.lang.Object class (as shown in the above figure)
It defines 2 sub classes i.e.; Exception and Error

2. java.lang.Exception:

java.lang.Exception is super class for all types of Exception
It extends java.lang.Throwable class
Exception are due to programmatic logic
And it is recoverable
Exception are categorized into checked exception and unchecked exception
Example: RuntimeException, SQLException, IOException, FileNotFoundException, ArithmeticException, NullPointerException

3. java.lang.Error:

java.lang.Error is super class for all types of Error
It extends java.lang.Throwable class
Error are due to lack of system resources
And it is non-recoverable
All error fall into unchecked exception category, as it is raised due to lack of system resources at runtime
It is out of programming scope as such type of error can’t predicted, may be well planned care can be taken to avoid these kind of Error
Example: VirtualMachineError, AssertionError, ExceptionInInitializerError, StackOverflowError, OutOfMemoryError, LinkageError, InstantiationError

Note: above mentioned Exception and Error are again categorized into checked and unchecked exceptions

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References:

Happy Coding !!
Happy Learning !!