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𝗝𝗮𝘃𝗮 𝗣𝗿𝗼𝗴𝗿𝗮𝗺𝗺𝗶𝗻𝗴 – 𝗖𝗦𝗣𝟯𝟰𝟭𝟯


A collection of my Java practice sets, coding exercises, and additional programs focused on strengthening and refining my programming skills.


Programs

Folder structure:

└── core-java-programming/
    ├── README.md
    ├── Java Programming.iml
    ├── Practice Sets/
    │   ├── Coding Set 1/
    │   │   ├── SET4P10.java
    │   │   ├── SET4P3.java
    │   │   ├── SET4P4.java
    │   │   ├── SET4P5.java
    │   │   ├── SET4P8.java
    │   │   ├── SET4P9.java
    │   │   ├── SET4P1/
    │   │   │   ├── college/
    │   │   │   │   ├── Admin.java
    │   │   │   │   └── Result.java
    │   │   │   └── main/
    │   │   │       └── Main.java
    │   │   ├── SET4P2/
    │   │   │   └── type/
    │   │   │       ├── bank/
    │   │   │       │   └── BankAccount.java
    │   │   │       ├── main/
    │   │   │       │   └── Main.java
    │   │   │       └── premium/
    │   │   │           └── PremiumAccount.java
    │   │   ├── SET4P6/
    │   │   │   └── payroll/
    │   │   │       ├── Main.java
    │   │   │       ├── finance/
    │   │   │       │   └── Finance.java
    │   │   │       ├── management/
    │   │   │       │   └── Manager.java
    │   │   │       └── staff/
    │   │   │           ├── Employee.java
    │   │   │           └── HR.java
    │   │   └── SET4P7/
    │   │       ├── document.txt
    │   │       └── SET4P7.java
    │   ├── Coding Set 2/
    │   │   ├── SET2P1.java
    │   │   ├── SET2P10.java
    │   │   ├── SET2P2.java
    │   │   ├── SET2P3.java
    │   │   ├── SET2P4.java
    │   │   ├── SET2P5.java
    │   │   ├── SET2P6.java
    │   │   ├── SET2P7.java
    │   │   ├── SET2P8.java
    │   │   └── SET2P9.java
    │   ├── Coding Set 3/
    │   │   ├── SET3P1.java
    │   │   ├── SET3P10.java
    │   │   ├── SET3P2.java
    │   │   ├── SET3P3.java
    │   │   ├── SET3P4.java
    │   │   ├── SET3P5.java
    │   │   ├── SET3P6.java
    │   │   ├── SET3P7.java
    │   │   ├── SET3P8.java
    │   │   └── SET3P9.java
    │   ├── Coding Set 4/
    │   │   ├── SET4P1.java
    │   │   ├── SET4P10.java
    │   │   ├── SET4P2.java
    │   │   ├── SET4P3.java
    │   │   ├── SET4P4.java
    │   │   ├── SET4P5.java
    │   │   ├── SET4P6.java
    │   │   ├── SET4P7.java
    │   │   ├── SET4P8.java
    │   │   ├── SET4P9.java
    │   │   └── StudentManagementSystem.java
    │   ├── Coding Set 5/
    │   │   ├── SET5P1.java
    │   │   ├── SET5P10.java
    │   │   ├── SET5P2.java
    │   │   ├── SET5P3.java
    │   │   ├── SET5P4.java
    │   │   ├── SET5P5.java
    │   │   ├── SET5P6.java
    │   │   ├── SET5P7.java
    │   │   ├── SET5P8.java
    │   │   ├── SET5P9.java
    │   │   └── .gitkeep
    │   └── Coding Set 6/
    │       ├── SET6P1.java
    │       ├── SET6P10.java
    │       ├── SET6P2.java
    │       ├── SET6P3.java
    │       ├── SET6P4.java
    │       ├── SET6P5.java
    │       ├── SET6P6.java
    │       ├── SET6P7.java
    │       ├── SET6P8.java
    │       ├── SET6P9.java
    │       └── .gitkeep
    └── src/
        ├── CountEachChar.java
        ├── CountFreqWords.java
        ├── GuessNumberGame.java
        ├── HelloJava.java
        └── removeDuplicateList.java

Main Programs (src)

1. HelloJava.java

What it does:

  • Stores a greeting in a String variable
  • Prints the message to the console

Key concepts:

  • main method
  • Variables and String
  • System.out.println()

Sample output:

Hello Java! My first program

2. GuessNumberGame.java

What it does:

  • Generates a random number from 1 to 100
  • Accepts user input using Scanner
  • Compares guess vs computer number and provides hints
  • Repeats until the correct guess is entered

Key concepts:

  • while (true) loop with break
  • Math.random()
  • Scanner
  • Ternary operator
  • Conditional branching (if / else if / else)

3. CountEachChar.java

What it does:

  • Reads a full line of text from the console
  • Counts how many times each character appears using a HashMap<Character, Integer>
  • Prints each character with its frequency

Key concepts:

  • Scanner.nextLine()
  • Iterating over toCharArray()
  • Map lookups and updates with containsKey

Sample output:

Enter the character
hello java
h:1
e:1
l:2
o:1
 :1
j:1
a:2
v:1

4. CountFreqWords.java

What it does:

  • Splits a user-provided sentence on spaces
  • Counts how many times each word occurs with a HashMap<String, Integer>
  • Prints each word followed by its frequency

Key concepts:

  • split(" ")
  • HashMap with String keys
  • Enhanced for loop for traversal

Sample output:

Enter the sentence
hello hello world
hello:2
world:1

5. removeDuplicateList.java

What it does:

  • Demonstrates removing duplicate integers from a list
  • Converts the list to a HashSet for uniqueness and back to an ArrayList
  • Prints the original and deduplicated lists (order of the unique list may vary)

Key concepts:

  • HashSet for enforcing uniqueness
  • Converting between List and Set
  • Printing collections

Sample output:

Original list: [1, 2, 1, 3, 4, 4]
Unique list: [1, 2, 3, 4]

Practice Sets

  • Coding Set 1 (Practice Sets/Coding Set 1): Renamed from Coding Set 4; object-oriented mini projects using packages and custom exceptions (college result processing, bank/premium accounts, payroll, orders/books, etc.).
  • Coding Set 2 (Practice Sets/Coding Set 2): Constructor practice across small classes (students, rectangles, employees, books, cars), arrays and averages, string/word processing, student arrays, and a basic bank account simulation with deposits.
  • Coding Set 3 (Practice Sets/Coding Set 3): Additional practice problems (see folder for details).

How to Compile and Run

Use the same pattern for any Java file:

cd <folder-containing-file>
javac FileName.java
java FileName

Examples:

  • For src: cd src
  • For Coding Set 1: cd "Practice Sets/Coding Set 1"
  • For Coding Set 2: cd "Practice Sets/Coding Set 2"

Student Programs

  • The earlier Coding Set 1 exercises (e.g., StudentManagementSystem.java) are kept in Practice Sets/Coding Set 1_original as a backup; they are not part of the new Coding Set 1 layout.

Topics Covered

  • Java basics and console output
  • Variables and data types
  • User input with Scanner
  • Loops and conditionals
  • Random number generation
  • Java Collections Framework (List, ArrayList, HashMap, Deque, Collections)
  • Adding, removing, searching, and reversing list elements
  • Sorting lists in ascending and descending order
  • Finding max/min values in collections
  • Array and list conversion (array <-> list)
  • Frequency counting with HashMap (lists, characters, words)
  • Removing duplicates from lists using Set
  • Finding common elements between lists
  • Basic stack operations using Deque