Exceptions in java

 Exceptions are one of the important concept of Java.

Exception: Exceptions are nothing but Run-time error which comes in program due to Logical errors in program like "Divide by Zero", "Null pointer Exception" etc. Exception is a class in java. Sometimes there is no Compilation Error (Syntactical error) in your program but due to some errors at run-time like wrong user input error may arise and your program will be abruptly closed.

Fig: Exception Class Hierarchy

So, To avoid your program to be closed abruptly, you must know how to handle Exception by using "Try-Catch" block. 

There are two types of Exception:

1) System Defined (handled by throws/throw)

2) User Defined (handled by throw) 

There are various Exception classes in java like:

•  ArrayIndexOutOfBoundsException
•  DivideByZeroException
•  IOException
• NullPointerException and many more...

For  more Details Refer following link:

http://java.meritcampus.com/t/150/Exceptions---why-java-throws-them?tc=mm116

http://java.meritcampus.com/t/152/Try-catch-block?tc=mm117