☕ SDET Java Interview Questions

A curated collection of Java coding solutions for the most commonly asked technical interview questions in SDET / Test Automation Engineer roles. All solutions are implemented from scratch — no built-in shortcuts — to demonstrate strong fundamentals.

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📋 Topics Covered

#	Problem	Concepts
1	Array Sort	Sorting without built-ins
2	Sorting Algorithms	Bubble, Selection, Insertion sort
3	Character Occurrences	HashMap, frequency counting
4	String Reverse	String manipulation
5	Factorial	Iteration
6	Palindrome Check	Two-pointer / string comparison
7	Largest & Smallest in Array	Array traversal
8	Binary Search	Divide and conquer, O(log n)
9	Prime Check	Number theory
10	Fibonacci Series	Iteration & recursion
11	Sum of Digits	Modulo arithmetic
12	Sum of Alphanumeric String	Character parsing
13	Array Intersection	HashSet, arrays
14	Stack Implementation	Data structures from scratch

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💡 Why This Repo Exists

SDET interviews frequently test core Java programming skills alongside automation knowledge. This repo focuses on the patterns that come up most often — array manipulation, string problems, searching, sorting, and basic data structures — all written with clarity and efficiency in mind.

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🧠 Sample Solution

Binary Search — O(log n) search on a sorted array:

public static int binarySearch(int[] arr, int target) {
    int left = 0, right = arr.length - 1;

    while (left <= right) {
        int mid = left + (right - left) / 2;

        if (arr[mid] == target)      return mid;
        else if (arr[mid] < target)  left = mid + 1;
        else                         right = mid - 1;
    }
    return -1; // not found
}

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🚀 How to Run

Prerequisites

• Java JDK 11+
• Any IDE (IntelliJ IDEA, Eclipse, VS Code)

Steps

# Clone the repo
git clone https://github.com/mail-adila/SDET_Java_Questions.git
cd SDET_Java_Questions

# Compile a file
javac BinarySearch.java

# Run it
java BinarySearch

Or simply open the project in IntelliJ IDEA or Eclipse and run any class directly.

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🎯 Key Concepts Demonstrated

• Arrays & String manipulation
• HashMap & HashSet usage
• Recursion vs. Iteration tradeoffs
• Classic sorting algorithms (Bubble, Selection, Insertion)
• Stack data structure implemented from scratch
• Time & space complexity awareness

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🔗 Related

• Blind 75 LeetCode (Python) — Advanced DSA practice
• Selenium Automation Framework — End-to-end test automation

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👩‍💻 Author

Adila Karim — LinkedIn · GitHub