Testdome Java Questions And Answers -

Alex is a junior developer preparing for a technical interview.
He opens TestDome to practice Java problems. Three questions appear.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class FileHandler 
public static String readFirstLine(String path) 
try (BufferedReader br = new BufferedReader(new FileReader(path))) 
return br.readLine();
 catch (IOException e) 
return "";

Why TestDome insists on this:

Question:
Implement classes Animal, Dog, and Cat. Animal has makeSound(). Dog prints "Woof", Cat prints "Meow". Create a method makeSound(Animal animal) that calls the appropriate sound.

Solution:

class Animal 
    public void makeSound() 
        System.out.println("Some sound");
class Dog extends Animal 
@Override
public void makeSound() 
System.out.println("Woof");

class Cat extends Animal 
@Override
public void makeSound() 
System.out.println("Meow");

public class Main 
public static void makeSound(Animal animal) 
animal.makeSound(); // polymorphic call

Key insight: TestDome checks if you correctly use @Override and runtime polymorphism. testdome java questions and answers

Sample Question:
Given a list of Product objects (name, price, category), return the sum of prices for all products in category "Electronics", but only if the price > 100. Use Java streams.

import java.util.HashSet;
import java.util.Set;
public class LongestConsecutive 
public static int longestConsecutive(int[] nums) 

Why this passes TestDome checks:

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

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: