Exception Handling in Java

Exception Handling in Java

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  www.java2blog.com EXCEPTION HANDLING
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  CONTENT Introduction Types of ExceptionHandling try block catch block finally block throw vs throws
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  INTRODUCTION An exception isan abnormal condition which occurs during the execution of a program. To handle the Exception we use exception handling mechanism. Exception handling helps to maintain the normal flow of execution of an application.
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  TYPES OF EXCEPTION Anexception that is checked at compile time is known as checked Exceptions. Examples of Checked Exception are IOException, SQLException, ClassNotFoundException. Checked Exception:
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  TYPES OF EXCEPTION Anexception that is not checked at compile time is known as an unchecked exception. Examples of Unchecked Exception are ArithmeticException, NullPointerException, NumberFormatException. Unchecked Exception:
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  TYPES OF EXCEPTION Errorsare irrecoverable. Exa- VirtualMachineError, StackOverFlowError, OutOfMemoryError. Error:
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  TRY BLOCK It mustbe followed either by finally block or Catch block. It must be used within a method. Try block is used to wrap the code that may throw an exception.
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  CATCH BLOCK A catchblock can be used only after the try block. All the catch block must be ordered from subclass exception to super class exception. The catch block is used to handle the exception. multiple catch block can be within a single try block.
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  FINALLY BLOCK We putthe cleanup code into the finally block like closing a file. A finally block will not execute only when If the program terminates through System.exit() or If causing a fatal error. A finally block is executed always whether the exception is handled or not.
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  THROW VS THROWS throwskeyword is used to declare an exception. It provides information to the programmer that there may occur an exception so It is programmer’s responsibility to provide exception handler so that the normal flow of application can be maintained throw keyword is used to explicitly throw an exception. It is generally used to throw a custom exception (User defined exception). It is used within a method body.
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