Java Helper Programs

• JavaDemo.java, Reads and writes to files. (by Jeff Klein) , Large print for overhead
  What this program does:
  
  1. Reads from a file line by line. Each line is read in as a String
  2. Uses the classes:
     BufferedReader and FileReader,
     BufferedWriter and FileWriter
  3. A "try-catch" block is used to catch an IOException errors that may be
     thrown by an error in the file opening.
• JavaDemo2.java (thanks to Kedar Hirve for as sistance) , Sample text file for JavaDemo2.java ,
  Large print for overhead
  What this program does:
  
  1. Reads from a file line by line. Each line is read in as a String.
  2. Uses a "try-catch" block to catch IOException's
  3. Imports class Vector and StringTokenizer from the package java.util
  4. Stores a Vector of objects of type Integer (this is different from int)
  5. StringTokenizer is used to collect a set of integers within a String.
  6. Defines three helper functions (or methods):
     getNumValue() returns the int value from a String
     getIntVector() collects a String of Integers into a Vector of Integers
     printVector() prints the Integer values within a Vector
     
  7. Uses the String method String.startsWith() to parse a String into a command
     and a number.
• JavaDemo2 Version 2 with separately compi led classes
  • The String Processing Class
  • The Vector Processing Class
  • Large Print Versions for Overhead:
    • JavaDemo2Ver2.java
    • StringProcessor.java
    • VectorProcessor.java
  What this program does:
  
  1. Same as JavaDemo2.java, except uses two separately compiled classes:
     class StringProcessor contains the method getNumValue() class VectorProcessor contains the two metods: getIntArray() and printArray()
  2. These separate classes are compiled within the same directory
• Reading Strings from the keyboard, Large print version for overhead.
  What this program does:
  
  1. Demonstrates keyboard input. echo prints the user's keyboard input
  2. Stops when the user types a "STOP" command
  3. Uses BufferedReader and InputStreamReader classes
  4. Shows keyboard input using System.in as the standard input file
• Java Array Examples , Large print for overhead
  What this program does:
  
  1. Shows examples of using a character array: char charArray[]
  2. Shows examples of using a String
  3. Printing the decimal, binary, and hexadecimal representations of a character
  4. Getting the length of an array: charArray.length (No parenthesis!)
  5. Getting the length of a String: string.length() (Parenthesis!)
• Java "Global" variables with static , Large print for overhead
  What this program does:
  
  1. Shows how "static" variables and functions defined outside of main() can be
     accessed directly
  2. Non-static variables can be accessed after you have created an instance
     of the class that you are inside
• Java Binary operators , Large print for overhead
  What this program does:
  
  1. Demostrates the use of the binary operators AND (&), OR (|), and NOT (~)
• Printing a Character Array in Binary and Hexad ecimal , Large print for overhead
  What this program does:
  
  1. Prints the elements of a character array in binary and hexadecimal form
• Converting from character to int
• Compiling and Running JavaDemo.java , Large print for overhead
• Java String API and Java StringBuffer API