Physicswallah Interview Questions and Answers

Using Java 8, find the first non-repeating character in a string.

• Use Java 8 streams to convert the string to a character array.

• Use Collectors.groupingBy to group characters by count.

• Filter out characters with count > 1 and find the first character with count 1.

Sum of all even numbers without using inbuild methods using stream api

• Create an array of numbers

• Use stream to filter out even numbers

• Use stream to sum up the filtered even numbers

Intermediate and terminal operators are used in Java streams to perform intermediate and terminal operations on elements.

• Intermediate operators are used to transform, filter, or manipulate elements in a stream before passing them to the next operation. Examples include map(), filter(), and sorted().

• Terminal operators are used to trigger the processing of elements in a stream and produce a result. Examples include forEach(), collect(), and reduce().

Exception handling in Spring Boot allows developers to gracefully handle errors and provide meaningful responses to users.

• Use @ControllerAdvice to handle exceptions globally

• Use @ExceptionHandler to handle specific exceptions

• Return custom error messages or responses to users

Various methods in RestApi include GET, POST, PUT, DELETE.

• GET - Used to retrieve data from the server. Example: GET /users

• POST - Used to send data to the server to create a new resource. Example: POST /users

• PUT - Used to update an existing resource on the server. Example: PUT /users/1

• DELETE - Used to delete a resource on the server. Example: DELETE /users/1

IOC is a design pattern where control is inverted, while DI is a technique to achieve IOC by injecting dependencies into a class.

• IOC stands for Inversion of Control, where the control of flow is inverted from the traditional top-down approach.

• DI stands for Dependency Injection, a technique used to implement IOC by injecting dependencies into a class from an external source.

• IOC is a design principle, while DI is a technique to achieve IOC.

• Example: In IOC, a framework controls ...read more

Annotation used in Spring framework to bind the HTTP request body to a method parameter.

• Used in Spring MVC to indicate that a method parameter should be bound to the body of the web request.

• Can be used with various data types like JSON, XML, etc.

• Helps in simplifying the process of handling request data in Spring applications.

Type casting in Java is the process of converting one data type into another.

• Type casting can be done implicitly or explicitly in Java.

• Implicit type casting is done when a smaller data type is converted to a larger data type, while explicit type casting is done when a larger data type is converted to a smaller data type.

• Example of implicit type casting: int num = 10; double result = num;

• Example of explicit type casting: double num = 10.5; int result = (int) num;