Exceptions

• Create and use Exceptions in Java
• Discuss how the finally clause actually works

try { ... code with possible exception ... } catch (ExceptionClassName e) { ... code to run if exception is thrown ... } finally { ... code run before finished with exception handling if not interrupted ... }

• you can have multiple catch clauses (for each type of possible exception)
• examples will be illustrated using posted demonstration programs
• TestException1.java (CIS 160): a non-compiling exception demonstration
• TestException2.java (CIS 160): a non-compiling exception demonstration
• TestException3.java (CIS 160): specifying but not catching an exception
• TestException4.java (CIS 160): catching an exception demonstration
• TestException5.java (CIS 160): displaying a special exception message
• TestException0.java: unchecked exceptions don't have to be specified
• TestException1.java: catching an unchecked exception
• TestException2.java: will not compile, exceptions not declared as thrown and not caught
• TestException3.java: declaring that exceptions are thrown
• TestException4.java: treating FileNotFoundException as an IOException
• TestException5.java: multiple catch blocks and "finally" processing
• TestException6.java: creating and throwing your own exceptions
• TestException7.java: creating and using exceptions with custom error messages
• TestException8.java: using try-with-resources
• TestException9.java: experimenting with finally
• TestException10.java: more experimentation with finally
• TestException11.java: even more experimentation with finally