LECTURE
8 NOVEMBER 2004

ASSIGNMENTS
Today 6:00 PM Assignment 3 Code
Fri CodeLab #10

What?
- reading and writing files

FILE INPUT

What?
- using files as input
- aka reading files

What?
- representing a file in java
- store info about a file in a particular location
How?
- java.io.File

What?
- paths
How?
- where something is located on your computer

What?
- full path: from the drive (Windows), or root (unix), including all of the directories on the way down
- relative path: assumes the current directory and just specifies the name

What?
- creating a file handle in Java
- File constructor takes a string with the name of the file
Example
  File f1 = new File("1108.txt");
  File f2 = new File("~/cs302/public/html/cs302/lecture/");

What?
- reading a file
- a file is just a sequence of 1's and 0's stored in memory
- to be able to read it, have to assume that these make sense as ASCII
How?
- use BufferedReader
  - instead of initializing with System.in, initialize with a File
  - like System.in, need an intermediate class: FileReader instead of InputStreamReader

What?
- java.io.FileStreamReader
  - translates file data bytes into a stream of characters
How?
- constructor
  - takes a File object or a String which is the file name
  - throws a FileNotFoundException if it can't find a matching file

What?
- reading a file
How?
- initialize BufferedReader with an instance of FileStreamReader initialized with a File object representing the file to be read
- use the readLine method to read a line of the file
Example:
  BufferedReader fileIn = new BufferedReader ( new FileReader ( "1108.txt" ) );

What?
- file reading issues
  - remember that readLine can cause an IOException which must be caught or propagated
  - readLine will return null if there's nothing left to read
  - use the new BufferedReader instance method close() to close the file when you are done reading it

Example:
- write a class to read a file and echo this output to the console