Java Training Course/Example Programs

All example Java programs can be obtained from a Git repository:

git clone https://github.com/gfis/jtc

Start with a greeting

• HelloWorld - one-liner: output a greeting

Arguments, assignment, elementary String and arithmetic operations

• StringAdd - concatenate argument strings 4 times and print them out
• IntAdd - add 4 integers 4 times and print them
  • IntMultiply - multiply 4 integers 4 times and print the product
  • LongMultiply - multiply 4 long numbers

Loops (while, for) and conditions (if), arrays ([])

• PowersOf2 - print the powers of 2
  • PowersOf2Check - check for increasing sequence
  • PowersOf2Backwards - print sequence backwards
  • PowersOf2Array - print sequence from an array

Sequences of conditions with switch, if - then - else if ...

• Selamat - print a greeting depending on the hour
  • SelamatSwitch - same with switch ... case ... default
• Number10 - print the numbers 1..10
  • Number10Method - print the numbers using a class method
• Month - print the indonese name of a month
• Weekday - print the indonese name of a weekday

Sequences of words

• Word1 - print all words with 1 letter
  • Word2 - print all words with 2 letters by 2 nested loops
  • Word3 - print all words with 3 letters
• Word3Cond1 - print words with 3 letters and vowel/consonant conditions, first version
  • Word3Cond2 - same, using a method, 2nd version
  • Word3Cond3 - same, output on a single line, 3rd version

Filtering files

A filter program reads a file, modifies all lines somehow, and writes them to another file.

• Filter1 - read a file and replace the vowels in each line
• FilterNumber - read a file and replace all digits by their indonese number words
• FilterMulti3 - read the modified output of Word3Cond3 and colorize the known words

Date and Calendars

• Age - enter a birthday and compute the elapsed years, months ... seconds up to now

Fractional arithmetic

• GreatestCommonDivisor - the first real algorithm
• Ratio - introduction to object oriented programming (static version)
  • Rational - object with methods for mathematical operators for exact fractions
  • RationalTestSwing, AboutRationalTest - GUI for the addition, subtraction, multiplication of two Rationals

Games

• PlayNim - play the Nim game with some number of sticks to be taken
  • PlayNimState - improve clarity of program logic by using a Discrete Finite State Automaton (DFSA)
  • PlayNimSwing, AboutPlayNim GUI for the Nim game
• ChessGame, ChessPlayer, ChessField, ChessPiece - interconnected set of classes for the display of a chess game using Unicode characters for the pieces

File Handling and Collections

• HexDump - hexadecimal dump of a file, maybe binary
• FilterURL - filter a file read from an URL (http://..., ftp://..., file://...)
• FilterTowns - read jtc/test/id_kota.lst with a list of indonesian towns, and extract the names and the number of inhabitants only
• SearchTown - store the town data in a HashMap, and look one up there
• SortTowns - store the town data in a TreeMap, and print a list sorted alphabetically by town name
• SearchAlice - read a text from an URL, for example Alice in Wonderland, collect and count the names therein, and print a sorted list
• WalkFileTree - run through a file directory with a subclass of FileVisitor and print the entries

Developper Information

• SystemProps - show the Java sysstem properties, the environment variables with their values, and the components of the system path
• TestRegex - input a Java regular expression and try to match test texts in a loop
  • TestRegexSwing, AboutTestRegex - Swing GUI version thereof

Subclasses and Factories

• Shape - class defining common properties and methods for geometrical forms, with output as an SVG (scalable vector graphics) file
• ShapeFactory - Factory pattern returning an instance of a Shape
• Circle, Square, Triangle, Hexagon - implementation of specific Shapes and their SVG representation