🔐 Password Strength Checker (Java)

A clean and beginner-friendly Java console application that validates password strength using
conditional logic and regular expressions.

📌 This project is designed for learning input validation, regex usage, and basic security rules.

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✨ Features

✔ Password length validation (8–16 characters)
✔ Must contain at least:

• 🔡 One lowercase letter
• 🔠 One uppercase letter
• 🔢 One digit
• 🔐 One special character (! @ # $ % ^ & *)
  ✔ Displays clear and specific error messages for invalid passwords

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🛠️ Technologies Used

• Java
• String.matches()
• Regular Expressions (Regex)
• Scanner (for user input)

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📂 Project Structure

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▶️ How to Run

1. Compile the program : javac PasswordChecker.java
2. Run the program : java PasswordChecker
3. Enter a password when prompted.

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🧠 Password Rules

Rule	Requirement
Length	8 to 16 characters
Lowercase	At least one a–z
Uppercase	At least one A–Z
Digit	At least one 0–9
Special Character	At least one !@#$%^&*

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📌 Sample Output

Strong password

Enter your Password: Abc@1234 Password was accepted and It is strong.

Weak password

Enter your Password: abc123 Doesn't contains UpperCase letter. Re-enter password. It is weak.

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🎯 Learning Outcomes

• Understand how password validation works
• Learn practical usage of String.matches() in Java
• Practice conditional logic and input handling
• Build a beginner-level security validation program

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🚀 Future Enhancements

• Add retry mechanism until a valid password is entered
• Refactor logic into a single regex pattern
• Add GUI using Swing or JavaFX
• Add unit tests for validation logic

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👤 Author

Puneeth Beginner Java & Cybersecurity Enthusiast

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⭐ Feel free to star the repository if you find it useful!