20+ TechBuddy Consulting Interview Questions and Answers

A hardworker puts in more effort, while a smartworker works efficiently and effectively.

• A hardworker may spend more time on a task, while a smartworker finds ways to complete it faster.

• A hardworker may rely on brute force, while a smartworker uses their skills and knowledge to solve problems.

• A hardworker may struggle with prioritization, while a smartworker knows how to focus on the most important tasks.

• A hardworker may burn out quickly, while a smartworker maintains a sustai...read more

Order of catch blocks in a try block in Java

• Specific catch blocks should come before general catch blocks

• If general catch block comes before specific catch block, it will result in a compile-time error

• If multiple catch blocks are present, only the first matching catch block will be executed

Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

• Abstract class can have constructors, member variables, and methods with implementation.

• Interface can only have abstract methods and constants.

• A class can implement multiple interfaces but can only extend one abstract class.

• Example: Abstract class - Animal with abstract method 'eat', Interface - Flyable with method 'fly'.

A trigger is a special type of stored procedure that automatically executes when certain events occur in a database.

• Triggers are used to enforce business rules, maintain data integrity, and automate repetitive tasks.

• They can be triggered by INSERT, UPDATE, or DELETE operations on a table.

• Examples of triggers include auditing changes to a table, updating related tables when a record is modified, or enforcing referential integrity.

final is a keyword used to declare constants, finally is a block used in exception handling, and finalize is a method used for cleanup.

• final is a keyword used to declare constants in Java, meaning the value cannot be changed once assigned. Example: final int x = 10;

• finally is a block used in exception handling to ensure a piece of code is always executed, whether an exception is thrown or not. Example: try { // code } finally { // cleanup code }

• finalize is a method in Java us...read more

Clustered indexes physically order the data in the table, while non-clustered indexes do not.

• Clustered indexes determine the physical order of data in the table, while non-clustered indexes do not.

• A table can have only one clustered index, but multiple non-clustered indexes.

• Clustered indexes are faster for retrieval of data, especially range queries, compared to non-clustered indexes.

• Non-clustered indexes are stored separately from the actual data, leading to faster insert an...read more

UNION combines and removes duplicates, UNION ALL combines without removing duplicates.

• UNION merges the result sets of two or more SELECT statements and removes duplicates.

• UNION ALL merges the result sets of two or more SELECT statements without removing duplicates.

• UNION is slower than UNION ALL as it involves removing duplicates.

• Example: SELECT column1 FROM table1 UNION SELECT column1 FROM table2;

• Example: SELECT column1 FROM table1 UNION ALL SELECT column1 FROM table2;

Code for connecting a Java application to a database

• Import the JDBC driver for the specific database

• Create a connection object using the DriverManager class

• Create a statement object to execute SQL queries

• Execute the query and retrieve the results

• Close the connection and release resources

Private keyword restricts access to member functions within the class while final keyword prevents overriding of functions.

• Private keyword is used to hide the implementation details of a class from the user.

• Final keyword is used to prevent the user from overriding a function in a subclass.

• Using private and final keywords together can ensure that the implementation details of a class are not modified by the user.

Private restricts access to the class itself, while final prevents inheritance and method overriding.

• Private access modifier restricts access to the class itself, while final access modifier prevents inheritance and method overriding.

• Private members are only accessible within the same class, while final classes cannot be extended and final methods cannot be overridden.

• Example: private int num; - num can only be accessed within the class. final class Example {} - Example class...read more

Garbage collection is an automatic memory management process that frees up memory occupied by objects that are no longer in use.

• Garbage collection is used in programming languages like Java, C#, and Python.

• It helps prevent memory leaks and reduces the risk of crashes due to memory exhaustion.

• Garbage collection works by identifying objects that are no longer in use and freeing up the memory they occupy.

• There are different algorithms for garbage collection, such as mark-and-swe...read more

finally is a keyword used in try-catch block, finalize is a method in Object class, and final is a keyword used for declaring constants.

• finally is used to execute a block of code after try-catch block

• finalize is called by garbage collector before destroying an object

• final is used to declare a constant variable or to make a class uninheritable

SQL query to fetch the nth highest salary from a table

• Use the ORDER BY clause to sort salaries in descending order

• Use the LIMIT clause to fetch the nth highest salary

Establishing a JDBC connection involves loading the driver, creating a connection, creating a statement, executing queries, and handling exceptions.

• Load the JDBC driver using Class.forName() method

• Create a connection using DriverManager.getConnection() method

• Create a statement using connection.createStatement() method

• Execute queries using statement.executeQuery() method

• Handle exceptions using try-catch blocks

A cursor in PL/SQL is used to retrieve and process multiple rows of data one at a time.

• Allows iteration over a result set

• Retrieves data row by row

• Can be used to update or delete rows in a table

• Must be declared, opened, fetched, and closed

Abstract class is a class with some implementation while Interface is a contract with no implementation.

• Abstract class can have constructors while Interface cannot

• Abstract class can have non-abstract methods while Interface cannot

• A class can implement multiple interfaces but can only inherit from one abstract class

• Abstract class is used when there is a need for common functionality among related classes while Interface is used when there is a need for unrelated classes to imp...read more

Garbage collection in Java is the process of automatically managing memory by deallocating objects that are no longer needed.

• Garbage collection helps in preventing memory leaks by reclaiming memory used by objects that are no longer referenced.

• Java uses a garbage collector to automatically manage memory, unlike languages like C++ where memory management is manual.

• Garbage collection in Java can be triggered by calling System.gc() or when the JVM determines that it is necessary...read more

JSON stands for JavaScript Object Notation, a lightweight data interchange format.

• JSON is used to transmit data between a server and a web application, as an alternative to XML.

• It is easy to read and write for humans and easy to parse and generate for machines.

• JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C family of languages.

• Example: {"name":"John", "age":30, "city":"New York"}

Data integrity refers to the accuracy, consistency, and reliability of data throughout its lifecycle.

• Data integrity ensures that data is accurate and consistent in storage and transmission.

• It involves maintaining the quality and reliability of data over time.

• Methods for ensuring data integrity include checksums, encryption, and error detection codes.

• Examples of data integrity violations include data corruption, unauthorized access, and data tampering.

Inheritance types in Java

• Java supports single and multiple inheritance through classes and interfaces respectively

• Single inheritance is when a class extends only one parent class

• Multiple inheritance is when a class implements multiple interfaces

• Java also supports hierarchical inheritance where multiple classes extend a single parent class

• Java does not support multiple inheritance through classes to avoid the diamond problem

Inheritance is a mechanism in object-oriented programming where a new class is created by inheriting properties of an existing class.

• Inheritance allows code reuse and promotes code organization.

• The existing class is called the parent or superclass, and the new class is called the child or subclass.

• The child class inherits all the properties and methods of the parent class and can also add its own unique properties and methods.

• Inheritance can be single, multiple, or multilevel...read more

An interface defines a set of methods that a class must implement.

• An interface is declared using the 'interface' keyword.

• All methods in an interface are public and abstract by default.

• A class can implement multiple interfaces.

• Interfaces can also extend other interfaces.

• Example: public interface MyInterface { void myMethod(); }