Java Exception Handling

The Java programming language uses exceptions to handle errors and other exceptional events. An exception is an event that occurs during the execution of a program that disrupts the normal flow of instructions. Many of the existing Java API's use exceptions to convey the error message to the caller.

The caller of the method needs to handle the exception correctly and it would enable smooth functioning of the system.

A method or program can use exceptions to indicate that an error occurred. To throw an exception, use the throw statement and provide it with an exception object, usually extends the Throwable class to provide information about the specific error that occurred. A method that throws an uncaught, checked exception must include a throws clause in its declaration.

A program can catch exceptions by using a combination of the try, catch, and finally blocks.

  • The try block identifies a block of code in which an exception can occur.
  • The catch block identifies a block of code, known as an exception handler, that can handle a particular type of exception.
  • The finally block identifies a block of code that is guaranteed to execute, and is the right place to close files, recover resources, and otherwise clean up after the code enclosed in the try block.

The try statement should contain at least one catch block or a finally block and may have multiple catch blocks.

The class of the exception object indicates the type of exception thrown. The exception object can contain further information about the error, including an error message. With exception chaining, an exception can point to the exception that caused it, which can in turn point to the exception that caused it, and so on.

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