Write a method that reads only the first line of a file efficiently. Return empty string if file is empty or not found.

Alex’s thoughts:

His final safe version:

import java.io.*;
public class FirstLineReader 
public static String getFirstLine(String filePath) 
try (BufferedReader br = new BufferedReader(new FileReader(filePath))) 
return br.readLine();
 catch (IOException e) 
return "";

✅ Efficient, resource-safe (try-with-resources), returns empty string on error/empty file.

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TestDome is widely used by employers to assess real-world Java skills. Unlike theoretical multiple-choice tests, TestDome focuses on writing correct, efficient, and maintainable code.

Below are common TestDome Java question patterns with solutions and explanations.

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Question:
Return indices of two numbers in an array that add up to a target. Assume exactly one solution. Optimize for time.

Solution (O(n) time, O(n) space):

import java.util.*;
public class TwoSum {
public static int[] findTwoSum(int[] nums, int target) {
Map<Integer, Integer> map = new HashMap<>();
for (int i = 0; i < nums.length; i++) 
int complement = target - nums[i];
if (map.containsKey(complement)) 
return new int[]  map.get(complement), i ;
map.put(nums[i], i);
return new int[] {}; // not reached given "exactly one solution"
}
}

Why TestDome likes it:

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