week-four.md

Explain the purpose and use of exception handling for error detection and correction.

• exception handling is used when the point at which an exception occurs is different from the point at which that error can or could have been corrected
• uncaught exceptions terminate the program
• the place where an exception is thrown is always different than the place it gets caught
  • because you can't or don't want to fix the error in the same place where it happened

Differentiate between checked and unchecked exceptions.

• unchecked exceptions are exceptions that happen during runtime
  • unchecked exceptions are subclasses of RuntimeException
  • they happen due to programmer error
  • the programmer can write code to avoid these exceptions
• checked exceptions are exceptions that are explicitly thrown in the code
  • checked exceptions are subclasses of Exception
  • they account for things that happen that are outside of the programmer's control
  • all checked exceptions must be caught or declared to be thrown
    • throws is used to show that a method throws checked exceptions
    • public void someMethod() throws FileNotFoundException, SomeOtherCheckedException
    • wherever the function is called, it has to either be in a method that is marked with throws or it has to catch the exception/s

Use the keywords throws, try, throw, catch, and finally to implement exception handling.

• throw indicates you've found an error, something that you can't fix
• try blocks wrap code that might throw an exception
• you can then catch exceptions in the catch block
• a caught exception doesn't terminate the program
• you can chain catch blocks to catch specific exception types
  • when chaining, you have to put the catch blocks in order of most to least specific exception types
  • e.g., put IOException after FileNotFoundException because FileNotFoundException is a subclass of IOException
    • if you caught them in the other order, IOException first, all IOExceptions and FileNotFoundExceptions would be caught by the first block (IOException), since FileNotFoundException is an IOException
• the finally block always runs, whether an exception was thrown or not

try
{
    var result = methodThatMightThrowException();
}
catch (SomeExceptionType e)
{
    // handle error here
}
catch (RuntimeException e)
{
    // handle error here
}
finally
{
    // this code will run no matter what
}

Define and use a domain-specific exception hierarchy.

• ???

Read and write binary files.

Read and write text files.

• line endings in Unix- vs. Windows-based machines
  • Windows machines end lines with \r\n
  • Unix-based machines end lines with just \n

Read and write serialized object files.

Define and explain the Serializable interface

Distinguish between random and sequential access files.