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