- An exceptions is a problem that occurs during program execution.
- Exceptions cause abnormal termination of the Program.
- Exception handling is a powerful mechanism that handles runtime errors to maintain normal application flow.
- An exception can occur for many different reasons. Some examples –
- A user has entered invalid data.
- A file that need to be opened cannot be found.
- A network connection has been lost in the middle of communications.
- Insufficient memory & other issues related to physical resources.
- Exception Handling –
- Exception can be caught using a combination of try & catch keyword.
- A try/catch block is placed around the code that might generates an exception.
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Syntax- try{ ..... }catch(Exception e){ ...... }
- A catch statement involves declaring the type of exception you are trying to catch.
- If an exception Occurs in the try block , the catch block that follows the try is checked .
- If the type of exception that Occurred is listed in catch block, the exception is passed into a method parameter.
- The Exception type can be used to catch all possible exception.
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Example- public class Mycalss{ public static void main(String args[]){ try{ int a[] = new int[2]; System.out.println(a[5]); }catch(Exception e){ System.out.println("An error Occurred"); } } } Output- An error Occurred.
- Without try/catch block this code should crash the program . a[5] does not exist.