NTT DATA, Inc. Java Back End Developer Interview Questions and Answers

Oops concepts in Java

• Encapsulation - hiding implementation details

• Inheritance - reusing code and creating parent-child relationships

• Polymorphism - multiple forms of a method or object

• Abstraction - creating abstract classes and interfaces

• Example: Encapsulation - using private variables and public methods

• Example: Inheritance - creating a subclass that inherits from a superclass

• Example: Polymorphism - using method overloa...read more

Altering columns in databases involves modifying the structure of a table by adding, deleting or modifying columns.

• Use ALTER TABLE statement to modify columns

• Add new columns using ADD COLUMN

• Delete columns using DROP COLUMN

• Modify columns using MODIFY COLUMN

• Changing column data type may result in data loss

Reversing a number in Java

• Convert the number to a string

• Use StringBuilder to reverse the string

• Convert the reversed string back to a number

To extract words from a line in Java, split the line using whitespace as delimiter.

• Use the split() method of String class

• Pass the whitespace regex as argument to split() method

• Iterate over the resulting array to get individual words

Generic collections provide type safety and reusability in software development.

• Generic collections allow us to store and manipulate objects of any type in a type-safe manner.

• They provide compile-time type checking, reducing the chances of runtime errors.

• They promote code reusability by allowing the same collection to be used with different types.

• Generic collections improve performance by eliminating the need for boxin...read more