Feathersoft Info Solutions Java Developer Trainee Interview Questions and Answers

Reverse a given string

• Iterate through the string from end to start and append each character to a new string

• Use StringBuilder or StringBuffer for better performance

• Convert the string to a character array and swap the first and last characters, then move towards the middle until the entire string is reversed

Program to find duplicate alphabets in a string

• Create a HashMap to store the frequency of each alphabet

• Iterate through the string and update the frequency in the HashMap

• Iterate through the HashMap and print the alphabets with frequency greater than 1

A Java program to find vowels from a given string.

• Create a string variable and initialize it with the given string.

• Use a for loop to iterate through each character of the string.

• Check if the character is a vowel using if statement and add it to a new string variable.

• Print the new string variable containing all the vowels.

Abstract classes are incomplete classes that cannot be instantiated. Anonymous classes are unnamed classes that can be created on the fly.

• Abstract classes are declared with the 'abstract' keyword and can have abstract and non-abstract methods.

• Anonymous classes are created using the 'new' keyword and can extend a class or implement an interface.

• Anonymous classes are often used for event handling and callbacks.

• Example of...read more

Inheritance in Java allows a class to inherit properties and methods from another class.

• Use the 'extends' keyword to create a subclass that inherits from a superclass

• The subclass can access all public and protected members of the superclass

• Example: class Dog extends Animal { ... }

• The 'super' keyword is used to call the superclass constructor or method

Controller in Spring is responsible for handling user requests and returning appropriate responses.

• Controller receives requests from the client and delegates them to appropriate handlers

• It maps the incoming requests to the corresponding handler methods

• It returns the response to the client after processing the request

• It can also handle exceptions and errors that occur during request processing

To configure server port in a Spring Boot app, modify the application.properties file.

• Open the application.properties file

• Add the following line: server.port=8080 (or any desired port number)

• Save the file and restart the application

Find the lowest number from an arraylist using streams

• Use stream.min() method to find the lowest number

• Pass Comparator.naturalOrder() to get the lowest number

• Handle empty list scenario using OptionalInt

Developed a web-based inventory management system for a retail store

• Used Java, Spring framework, and MySQL for backend development

• Implemented user authentication and authorization using Spring Security

• Designed the frontend using HTML, CSS, and JavaScript

• Integrated barcode scanner for efficient inventory management

• Conducted unit testing using JUnit and integration testing using Selenium

• Deployed the application on AWS EC...read more

Refresh scope is used in Spring framework to control the lifecycle of beans.

• Refresh scope is used to create a new instance of a bean every time it is requested.

• It is useful when the state of a bean needs to be reset on every request.

• To use refresh scope, add @RefreshScope annotation to the bean definition.

• Example: @Bean @RefreshScope public MyBean myBean() { return new MyBean(); }