Java Software Developer Interview Questions and Answers for Freshers

Design a rate limiter service to control the number of requests a user can make in a given time frame.

• Use token bucket or leaky bucket algorithms for rate limiting.

• Implement a sliding window mechanism for more granular control.

• Store user request counts in a distributed cache like Redis.

• Set limits per user or IP address, e.g., 100 requests per minute.

• Provide feedback to users when limits are exceeded, e.g., HTTP 429 status.

Polymorphism is the ability of a single function or method to operate on different data types. Types include compile-time and runtime polymorphism.

• Polymorphism allows a single function to work with different data types.

• Compile-time polymorphism is achieved through method overloading.

• Runtime polymorphism is achieved through method overriding.

• Example: Overloading a method with different parameter types.

• Example: Overriding a method in a subclass to provide specific implementatio...read more

Inner join returns only the rows that have matching values in both tables, while left join returns all rows from the left table and the matched rows from the right table.

• Inner join: returns rows where there is a match in both tables

• Left join: returns all rows from the left table and the matched rows from the right table

• Example: Inner join - SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id

• Example: Left join - SELECT * FROM table1 LEFT JOIN table2 ON table1.id = ...read more

I am passionate about programming and Java is a versatile language with a wide range of applications.

• Java is widely used in the industry and has a strong community support.

• Java is platform-independent and can be used to develop applications for various devices.

• Java has a rich set of libraries and frameworks that make development faster and easier.

• Java is used in a variety of domains such as web development, mobile app development, and enterprise software development.

• I have ex...read more

Object-oriented programming concepts in Java

• Encapsulation: bundling data and methods together

• Inheritance: creating new classes from existing ones

• Polymorphism: using a single interface to represent different types

• Abstraction: hiding implementation details and providing a simplified view

• Encapsulation: grouping related data and methods into objects

The .equals() method in Java is used to compare the contents of two objects for equality.

• The .equals() method is used to compare the actual contents of two objects, unlike the == operator which compares object references.

• It is commonly used with String objects to check if two strings have the same sequence of characters.

• Example: String str1 = "hello"; String str2 = "hello"; boolean result = str1.equals(str2); // result will be true