Errors

　　An Error is any unexpected result obtained from a program during execution.

　　Unhandled errors may manifest themselves as incorrect results or behavior, or as abnormal program termination.

　　Errors should be handled by the programmer, to prevent them from reaching the user.

Some common types of program fault

　　Logic errors - the program does not match the specification (e.g. the requirements, or design)

　　Divide by zero

　　Exceeding array bounds

　　Using an uninitialised variable/object

　　…

Error Handling

　　Traditional Error Handling

Return a special value,

　　e.g., -1 or EoF

　　Shortcoming:

　　hard to distinguish different errors

　　programmer must remember the meaning of different values

　　Have a global error handling routine, and use some form of “jump” instruction to call this routine when an error occurs

　　Shortcoming:

　　“jump” instruction (GoTo) are considered “bad programming practice”

Exceptions in Java（異常）