Software Engineer Interview Questions for entry and Mid Level – Part1


This post will have most important interview questions which used to ask in most of the reputed companies like Google, Amazon, NetApp, Wells Fargo, Wipro, Infosys, TCS, SAP etc.
We are just adding Questions to this post and the technical reader will post the answers using comments sections.
We will provide all questions with a proper explanation later in the separate post and will link to this post.

Hope reader will enjoy the post and helps us to get the proper answers.

Please follow below section for the list of questions –

  • What is exception handling?

  • What do you understand by final, finally and finalize?

  • What are the features of Object Oriented Language?

  • What are abstract classes and how they are different from interfaces?

  • What is multithreading, with an example?

  • How do you create threads (extending Thread class or implementing a Runnable interface), and why?

  • What are different collections?

  • What are key differences between HashMap and HashTable?

  • Why and how HashCode/Equals method should be overridden?

  • How would you store and fetch objects in a HashMap/HashTable (implementation of Comparable and Comparator interface)?

  • Describe Singleton/MVC/Factory Methods design pattern?

  • How can a Singleton be created (in the multithreaded environment also)?

  • What are joins in SQL (for example)?

  • Basic Unix commands (e.g. ps, kill, ftp, su).

  • Case studies for Subqueries?
    1. There are 4 columns in a table and one of them is a telephone number. Write a query to retrieve the name of the employee whose age is less than 25 and does not have a phone number.
    2. You cannot utilize functions such as IS NULL, has to be done logically using a sub query.

  • What are different types of Statements in JDBC, with usage?

  • Multithreading with Static variables.

  • What is Compile time and Runtime Polymorphism?

  • Basics of Memory Management in JVM.

  • Can a class be Final?

  • What are some of the Implicit objects in a JSP?

  • What are some of the design patterns that Struts Uses?

  • Which class in struts acts as a front controller?

  • Are action classes in struts stateful or stateless? What is its implication?

  • What is the difference between forward and redirect?

  • Explain different attributes in struts config file? Relationship between form beans and action classes? One to one, one to many?

  • Design an object model for message formatting and processing module. (Messages have header and footer, can be of different formats, processing depends on the content inside the header, processing may need to be done in multiple steps, again depending on the content)

  • Design a multithreaded server which can handle messages in Q27 concurrently. (related to a specific project in the work exp)

  • Explain the lifecycle of a thread.

  • Explain left outer join. Write a query involving the use of subqueries.

  • Explain the ACID properties of transactions.

  • Explain the various isolation levels. (Dirty read, Phantom read, completely serializable). Explain the significance of each.

  • Are you aware of end points in a transaction?

  • How will you provide transactional support in a standalone java application? What are the issues to keep in mind? (The application depends on external IO systems). Specific to the project in work exp.

  • How does a hashmap work?

  • How do u override equals and hashcode methods?

  • What is the difference between overload and override?

  • What is stringbuilder and stringbuilder?difference between them?

  • How do u implement threads?

  • What is singleton pattern?how do u implement it?

  • What is factory pattern?

  • A puzzle. There is a 4*4 jail.each cell has one prisoner.the top right cell has JamesBond in it. The left bottom cell is the only exit from the prison. Every cell has a door to its adjacent wall except the boundaries.  Whenever JB moves to another cell, he kills that prisoner if he is alive. If the prisoner is dead, JB himself dies.  The next morning jailer sees that all prisoners are dead and JB has escaped. How is it?

  • Difference between PATH and CLASSPATH. How do u set them?

  • Unix commands. What is ls command? What is “Is –a”?

  • Employee table

Name deptid  salary                                      deptid                name

——————————                                               ———————————–

Xxx       tech     100                                          tech                 technology

Xxx       tech     200                                          hr                     human resource         

Xxx       hr         300

Xxx                   400

  • Write a query to get unique rows. Display the name of the employee and the sum of the salary department wise
  • Write a query to get employee name and department name
  • Same as question 1 , but also get the row with deptid as null

  • What is hashing.Write Hash code and equals method code for Emp class. What exception may be thrown here.

  • Exception handling(Runtime and compile-time exceptions).


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