Doyen Systems Interview Questions and Answers

Q1. Normal question about past experience
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Q2. When you can join and all
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SQL test on Select query, insert, create

Q1. What are the main principles of the Java
Ans. 
Main principles of Java include object-oriented programming, platform independence, and automatic memory management.
• Object-oriented programming: Java is based on classes and objects, allowing for encapsulation, inheritance, and polymorphism.

• Platform independence: Java code can run on any platform that has a Java Virtual Machine (JVM) installed.

• Automatic memory management: Java uses garbage collection to automatically m
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Q2. What is the different between == and equals method
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The == operator compares the memory addresses of two objects, while the equals method compares the content of two objects.
• The == operator is used to compare the memory addresses of two objects in Java.

• The equals method is used to compare the content of two objects in Java.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will return false, but str1.equals(str2) will return true
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Q1. What is jdk, string related questions, basic java oops questions?
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Os, cloud computing, DBMS, networks, ai and ml mcq questions were asked

Q1. What are oops concepts in java, explain real time scenario
Ans. 
OOPs concepts in Java include inheritance, polymorphism, encapsulation, and abstraction.
• Inheritance allows a subclass to inherit properties and methods from a superclass.

• Polymorphism allows objects to take on multiple forms and behave differently based on their context.

• Encapsulation hides the implementation details of an object and only exposes necessary information.

• Abstraction allows for the creation of abstract class...read more
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Q2. Uses of interface, inheritance
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Interfaces define contracts for behavior, while inheritance allows for code reuse and polymorphism.
• Interfaces allow for loose coupling and abstraction, enabling multiple implementations of the same behavior.

• Inheritance allows for code reuse and extension of existing classes, reducing code duplication.

• Polymorphism allows objects of different classes to be treated as if they were of the same class, simplifying code and i
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Q3. SQL query for join of tables
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SQL query for joining tables
• Use JOIN keyword to combine two or more tables based on a related column

• Specify the columns to be selected using SELECT keyword

• Use ON keyword to specify the condition for joining the tables

• Different types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN
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Q4. Java concepts used in your project
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Used Java concepts such as inheritance, polymorphism, and exception handling in my project.
• Implemented inheritance to create a base class and derived classes with specific functionalities.

• Utilized polymorphism to allow objects of different classes to be treated as if they were of the same class.

• Implemented exception handling to handle errors and prevent program crashes.

• Used interfaces to define a set of methods that a ...read more
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Q5. Overloading vs overriding, practical uses
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Overloading is having multiple methods with the same name but different parameters. Overriding is having a method in a subclass with the same name and parameters as a method in the superclass.
• Overloading is used to provide different ways to call a method with different parameters

• Overriding is used to provide a specific implementation of a method in a subclass

• Overloading is resolved at compile-time while overriding is r...read more
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Normal apptitude queations were asked in this round

Q1. Questions on javascript Basic of HTML, CSS
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