Advanced Computer Programming (Java)

Java programs I wrote for Advanced Computer Programming and Lab at REVA University, Bengaluru (B.Tech, 3rd semester, 2018). Coming from a C background, this was the first real OOP course — everything from System.out.println to threads, collections and a working Swing calculator, plus the lab exercises in lab/.

172 programs. One class per file, filename matches the class, no packages except the one folder that teaches packages.

Structure

Folders in the order the topics were taught:

Folder	What's in it	Programs
01-basics/	Printing, variables, casting, Scanner input, operators	14
02-control-flow/	if/else, switch, loops, the usual number programs, patterns	18
03-arrays/	1D and 2D arrays, searching, the three sorts, matrix operations	13
04-strings/	String methods, StringBuffer/StringBuilder, == vs .equals	13
05-classes-and-objects/	Constructors, this, static, overloading, encapsulation	15
06-inheritance/	extends, super, overriding, dynamic dispatch, abstract, final	12
07-interfaces-and-packages/	Interfaces, default methods, a real mypack package	11
08-exception-handling/	try/catch/finally, throw, throws, a custom exception	10
09-multithreading/	Thread, Runnable, join, synchronized, wait/notify	10
10-collections/	ArrayList, LinkedList, Vector, sets, maps, Comparator	13
11-generics/	Generic classes and methods, bounded types, a generic stack	6
12-file-io/	Readers/writers, byte streams, File class, serialization	9
13-gui-swing/	JFrame, events, layouts, a working calculator GUI	8
14-projects/	The big menu-driven programs	6
lab/	The 14 numbered lab exercises with their problem statements	14

Compiling and running

Everything is plain JDK — no build tool, no IDE project files. Compile a file, run the class:

cd 02-control-flow
javac Factorial.java
java Factorial

The one exception is the package demo, which has to be compiled from the folder root so mypack resolves:

cd 07-interfaces-and-packages
javac mypack/*.java PackageTest.java
java PackageTest

The Swing programs (13-gui-swing/, lab/Lab14_EventHandling.java) open a window, so they need a desktop session — everything else runs in a terminal.

The code was written on Java 8 in the lab and compiles unchanged on current JDKs. Vector and Stack are in the collections folder because they were still on the syllabus, not because anyone should use them.

Things this course beat into me

• == on two strings compares references, not contents. 04-strings/StringCompare.java exists because of the hour that lesson cost me.
• scanner.nextInt() doesn't consume the newline, so a following nextLine() reads an empty string. The fix (an extra nextLine()) is in 01-basics/ScannerInput.java.
• Without synchronized, two threads incrementing the same counter 10000 times each don't produce 20000. 09-multithreading/SynchronizedDemo.java prints the right answer; getting there took a while.
• The parent-class exception has to come last in a multi-catch, super() has to be the first line, and the compiler will remind you of both, loudly.

Projects

The six in 14-projects/ are menu-driven console programs built around a class plus an ArrayList — a student record system, a bank account with a mini statement, a small library manager, a five-question quiz, a two-player tic-tac-toe with full win/draw detection, and a matrix calculator. 13-gui-swing/CalculatorGUI.java is the same calculator idea with buttons.

Lab

lab/ holds the numbered exercises from the lab manual. Each file opens with the problem statement and the compile command, because the lab record required both. Lab11_ThreadDemo (three threads printing squares, cubes and randoms) is the one everyone remembers — the interleaved output finally makes threads feel real.