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Lead Java Developer Interview Questions


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EPAM Systems
Lead Java Developer was asked...22 May 2017

Coding test: 1. Given a string, find out if there's repeat characters in it. 2. SQL. Given a Customer table and a Payment table (with Customer ID as primary and foreign key), write a query to output a list of customers who have not paid their bills in the last 3 months.

15 Answers

Did well on the first Java coding test. Solution using Hashset. Not so well on the SQL query. Able to give a query, but a few errors in it I am sure. Also there was a second questions regarding the SQL query, which we didn't have time to get to. So that was another bad thing. I am pretty sure I did not pass. But good learning experience. Less

import java.util.*; public class test { public static void main(String[] args) { String str = "abdc"; char[] arr = str.toCharArray(); HashSet set = new HashSet(); for (char i : arr ) { set.add(i); } if((set.size()) == (arr.length)) System.out.println("unique character"); else System.out.println("repetition"); } } Less


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Applied Materials

Input is a string like "AAAAABBCCAA" and it should print "5A2B2C2A". 5 being the continuous number of occurance for character 'A'. Same is with other characters also.

3 Answers

let string:String = "AAAAABBBVVVCVCAA" let characters = Array(string) var counter:Int = 1 var newArray:[String] = [String]() let lastCount = characters.count - 1 for count in 0...(characters.count - 2) { if characters[count] == characters[count + 1] { counter = counter + 1; }else { newArray.append("\(counter)\(characters[count])") counter = 1 } if lastCount == count + 1 { newArray.append("\(counter)\(characters[count])") } } print(newArray) Less

public static void main(String[] args) { String s = "AAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBCC"; Set set = new HashSet(); char b = 0; int count = 1; String newString = ""; for (int i = 0; i 0) { b = s.charAt(i - 1); } char c = s.charAt(i); if (!set.add(c)) { count++; } else { if (b != 0) { newString = newString + b + count; count = 1; } } } newString = newString + b + count; System.out.println(newString); } Less

public static void main(String[] args) { String s = "AAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBCC"; Set set = new HashSet(); char b = 0; int count = 1; String newString = ""; for (int i = 0; i 0) { b = s.charAt(i - 1); } char c = s.charAt(i); if (!set.add(c)) { count++; } else { if (b != 0) { newString = newString + b + count; count = 1; } } } newString = newString + b + count; System.out.println(newString); } Less


1) Update the existing map without creating another map. 2) Write code to show the deadlock. 3) Find the maximum number from the given array. 4) Write the signature of service returning all the records from the provided table. 5) Explain about the Json format.

3 Answers

I also had the similar experience here, all other people seem to be normal but this HR was some sick person, so assume that HR policies will be similar here. I am happy to decide that I will not be going here. Less

Thanks for the feedback, to me also HR gave the same dialogue about salary. And I decided to try for some other organization rather such fake company. I also believe the ratings given here 4.6 is fake. Less

It is a company of fraud people, so better to have distance with this company...

JPMorgan Chase & Co

Did you work on any caching technologies

2 Answers


Yes. Mentioned that ehCache. Didn't go into detail.


I didn't get unexpected questions. All question were related to my technical skills and to my previous working experience

2 Answers



JPMorgan Chase & Co

Tell me about Java 8 features. After I mentioned in lambda expressions etc, he asked me, what is new with interfaces in Java-8.

2 Answers

I started saying that 'default' keyword is introduced. Now a method can be declared with keyword 'default'. He interrupted me and said there is no keyword called 'default' Less

forEach() method in Iterable interface default and static methods in Interfaces Functional Interfaces and Lambda Expressions Java Stream API for Bulk Data Operations on Collections Java Time API Collection API improvements Concurrency API improvements Java IO improvements Miscellaneous Core API improvements Less

EPAM Systems

About the topics as mentioned in description. Gave one little code using lambda expression to find the problem. Then gave another code & asked to reduce its number of lines to one line using jdk8 feature.

2 Answers

For code reduction problem, he was expecting me to suggest Optional, which I suggested initially but in the end I said that I will never suggest to use Optional here to sacrifice the readability of the code, just to shorten the code. Which I think, he didn't like. Less

This interviewer was expecting me to say 'Optional', which I even said in the start but by the end I suggested not to use Optional here just to reduce the code size & sacrificing the code readability. And that thing also didn't go well. As many kids just mug-up something from internet & start iterating the same everywhere to show their pseudo intelligence & thinking everyone around is fool. Less

EPAM Systems

What if we insert with key null to a HashMap?

2 Answers

Didn't know, however, it's a very edge case, you can insert and the hashcode will be 0, so it's identifying the '0' bucket. Less

HashMap allows null as both key and value, as well. So you can associate a value to null key. However, TreeMap throws a NullPointerException if you try to put a key with null value. Less


Find the units of snow can be trapped in the given array of building of various heights. It is like 'Trapping Rain Water' problem in Leetcode

2 Answers

I was not able to code for it.

Check Leetcode problem - 42

American Bureau of Shipping (ABS)

Design the Vending machine using Microservices.

2 Answers

Many times, if you are asked about open ended questions then can assume that you are not going to be selected, as many times Interviewer will be thinking opposite to your answer or will be expecting more or something else. So chances reduce. Less

Believe it or not, current such Leads or delivery heads are just wasting the time of candidates like they waste money in their projects by just fooling around. Less

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