Checked and Unchecked Exceptions

• Categories aren't perfect:
  • Scanner.nextInt throws unchecked InputMismatchException
  • Programmer cannot prevent users from entering incorrect input
  • This choice makes the class easy to use for beginning programmers
• Deal with checked exceptions principally when programming with files and streams
• For example, use a Scanner to read a file

  String filename = . . .;
  FileReader reader = new FileReader(filename);
  Scanner in = new Scanner(reader);

• But, FileReader constructor can throw a FileNotFoundException