Trantor Interview Questions and Answers

Abstract class can have implementation while interface cannot. A class can implement multiple interfaces but only extend one abstract class.

• Abstract class can have constructors while interface cannot.

• Abstract class can have non-abstract methods while interface can only have abstract methods.

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

• Abstract class can have instance variables while interface cannot.

• Abstract class is used for code reusability w...read more

Primary key uniquely identifies a record in a table, while unique key ensures that all values in a column are distinct.

• Primary key is used to enforce entity integrity, while unique key enforces domain integrity.

• A table can have only one primary key, but multiple unique keys.

• Primary key can't have null values, while unique key can have null values.

• Primary key is automatically indexed, while unique key may or may not be indexed.

Arrow functions are a concise way to write functions in JavaScript.

• Arrow functions have a shorter syntax compared to regular functions.

• They do not have their own 'this' value, instead, they inherit 'this' from the surrounding context.

• Arrow functions are always anonymous and cannot be used as constructors.

• They are commonly used in React components for event handlers and callback functions.

Interfaces in Java provide a way to achieve abstraction and multiple inheritance.

• Interfaces define a set of methods that a class must implement.

• They allow for loose coupling between classes.

• Interfaces can be used to achieve polymorphism.

• Java does not support multiple inheritance, but interfaces provide a way to achieve it.

• Interfaces are used extensively in Java frameworks like Spring and Hibernate.

To join three different tables in SQL, you can use the JOIN keyword along with the appropriate join conditions.

• Use the JOIN keyword to combine tables based on a common column

• Specify the join conditions using the ON keyword

• You can join more than two tables by chaining multiple JOIN statements

• Different types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

Overloading is having multiple methods with the same name but different parameters. Overriding is implementing a method in a subclass that already exists in the parent class.

• Overloading is compile-time polymorphism while overriding is runtime polymorphism.

• Overloading is used to provide different ways of calling the same method with different parameters.

• Overriding is used to provide a specific implementation of a method in a subclass that is already defined in the parent class...read more

Yes, exception handling is required in a big project.

• Exception handling helps in identifying and resolving errors during runtime.

• It improves the stability and reliability of the application.

• Exceptions can occur due to various reasons like network issues, server errors, or user input errors.

• Handling exceptions gracefully prevents the application from crashing and provides a better user experience.

• It allows for proper error logging and debugging, making it easier to identify an...read more

Access specifiers in Java are keywords that determine the visibility of a class, method, or variable.

• There are four access specifiers in Java: public, private, protected, and default.

• Public: accessible from anywhere in the program.

• Private: accessible only within the same class.

• Protected: accessible within the same class, subclasses, and same package.

• Default: accessible within the same package only.