Finicity

Core Java

• Explain JVM

• Default size of JVM

• Default size of heap

• How to increase the size of heap

• What goes in the stack and what goes in the heap in detail

• What is a weak reference

• What is a weak-hashmap

• How does GC work

• How to invoke GC

• What is the finalize method and in which class does it belong to

• Is the Object class an abstract class

• Difference between vector and arraylist and which is faster

• Stack and queue

• Queue implementations

• Explain the concurrency package and what has been added

• What is latchcount

• What is a cyclic barrier

• What is an atomic integer

• What is volatile

• What is serialization, what is transient

• What is callable and how is it different from runnable

• What is the executor framework and how many types are there

• What is a future object

Miscellaneous

• What messaging have you worked on (e.g. JMS, RabbitMQ, etc.)

• What databases have you worked on

• Can there be two JVMs on a single machine

AWS

• What services do you know in AWS

• What database is used in AWS

• Writing stored procedures

Java 8

• What is a functional interface

• What is the Optional class

• What is the Stream API

• Why is the Stream API lazy

• Writing a lambda expression to create a thread and print your name

• Output of the following programs:

List<Integer> numbers = Arrays.asList(1,2,3);
numbers.stream().filter(n -> {
  System.out.printf("Filtering => %d \n", n);
  return n%2 == 0;
});

List<Integer> numbers = Arrays.asList(1,2,3);
numbers.stream().filter(n -> {
  System.out.printf("Filtering => %d \n", n);
  return n%2 == 0;
}).map(n -> {
  System.out.printf("Mapping => %d \n", n);
  return n * 2;
});

public class Demo {
  public static void main(String args[]) {
    int[] array = new int[10];
    printArray(array);
  }

  public void printArray(int[] array){
    for(int i : array)
      System.out.println(i);
  }
}

Spring Boot

• What is the default server provided by Spring Boot (e.g. Tomcat, Netty, etc)

• What is the default underlying implementation of Spring Boot JPA

• Steps to implement security in Spring Boot

• How to change the default implementation of ORM in Spring Boot

• Difference between webservice and RESTful services

• What is JAX-RS

Git

• What is the difference between git pull and git fetch

Database

• What is indexing and why is it used

• What is a primary key

• Can you index a primary key

• How to write a stored procedure

Microservices

• What is microservice architecture

• What is vertical and horizontal scaling

• How to handle failover for a database server