10+ Johnson Controls Interview Questions and Answers

Interfaces define a contract for behavior, while abstract classes provide partial implementation.

• Interfaces only define method signatures, while abstract classes can have both abstract and concrete methods.

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

• Interfaces are used for loose coupling and flexibility in design.

• Abstract classes are used for code reuse and to enforce a common implementation among subclasses.

Stored procedures are used to perform a set of actions, while functions return a single value.

• Stored procedures are precompiled and stored in the database, while functions are compiled at runtime.

• Functions can be used in SQL statements, while stored procedures cannot be used in SQL statements.

• Functions can be called from within stored procedures, but stored procedures cannot be called from within functions.

Virtual keyword is used to declare a method in a base class that can be overridden in a derived class. Override keyword is used in the derived class to override the implementation of the virtual method.

• Virtual keyword is used in the base class to declare a method that can be overridden in the derived class

• Override keyword is used in the derived class to override the implementation of the virtual method

• Virtual methods provide a way for a base class to define a default implemen...read more

SOLID principles are a set of five design principles for writing maintainable and scalable code.

• Single Responsibility Principle (SRP) - a class should have only one reason to change

• Open-Closed Principle (OCP) - a class should be open for extension but closed for modification

• Liskov Substitution Principle (LSP) - subtypes should be substitutable for their base types

• Interface Segregation Principle (ISP) - clients should not be forced to depend on interfaces they do not use

• Depend...read more

Program to find the second largest element from a 4-digit number

• Convert the number to a string and split it into an array of characters

• Sort the array in descending order

• Return the second element of the array

Singleton design pattern restricts the instantiation of a class to a single instance and provides a global point of access to it.

• Used when only one instance of a class is required throughout the system

• Provides a global point of access to the instance

• Implemented using a private constructor, static method, and static variable

• Example: Logger class, Database connection class

No, C# does not support multiple inheritance.

• C# only supports single inheritance, where a class can inherit from only one base class.

• However, C# does support multiple interface inheritance, where a class can implement multiple interfaces.

• This is achieved using the 'interface' keyword instead of 'class'.

Routing in MVC is done through the use of routes, which map URLs to controller actions.

• Routes are defined in the RouteConfig.cs file in the App_Start folder

• Routes consist of a URL pattern and a corresponding controller action

• Routes can also include optional parameters and constraints

• Routing is done through the use of the ASP.NET routing engine

• Routing can be customized by creating custom route handlers

Singleton design pattern restricts the instantiation of a class to a single instance and provides a global point of access to it.

• Used when only one instance of a class is required throughout the system

• Provides a global point of access to the instance

• Implemented using a private constructor, static method, and static variable

• Example: Logger class in Java

Extension methods are static methods that allow adding new functionality to existing types without modifying the original type.

• Extension methods are defined in a static class.

• They must be declared with the 'this' keyword before the first parameter.

• They can be called as if they were instance methods of the extended type.

• Extension methods can be used to add functionality to built-in types or custom types.

• Example: adding a method to the string type to convert a string to title c...read more

Filters in MVC are used to intercept and modify HTTP requests and responses.

• Filters can be used to implement authentication and authorization.

• They can also be used for caching and logging.

• Examples of filters include AuthorizationFilter, ActionFilter, and ExceptionFilter.

Indexes in SQL are used to improve the performance of queries by allowing faster data retrieval.

• Indexes are created on one or more columns of a table.

• They work like a book index, allowing the database to quickly find the data.

• Indexes can be clustered or non-clustered.

• Clustered indexes determine the physical order of data in a table.

• Non-clustered indexes create a separate structure to store the index data.

• Indexes should be used carefully as they can slow down data modification...read more

Dependency injection is a design pattern used to remove hard-coded dependencies and make code more modular and testable.

• Dependency injection involves injecting dependencies into a class rather than having the class create them itself.

• This allows for easier testing and swapping out of dependencies.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.

• Examples of dependency injection frameworks include Spring and Guice.