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Essential Classes
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Exceptions
Summary
A 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 — a descendant of
Throwable — 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.
