Infosys Java Developer Interview Questions, Process, and Tips

Q1. Method overloading vs overriding?
Ans. 
Method overloading is having multiple methods in the same class with the same name but different parameters, while method overriding is redefining a method in a subclass with the same name and parameters as in the superclass.
• Method overloading involves multiple methods with the same name but different parameters.

• Method overriding involves redefining a method in a subclass with the same name and parameters as in the sup...read more
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Q2. String immutable reason?
Ans. 
String in Java is immutable to ensure thread safety, security, and optimization.
• Immutable strings are thread-safe as they cannot be modified concurrently.

• Immutable strings prevent security vulnerabilities like SQL injection.

• Immutable strings allow for string interning, optimizing memory usage.

• Example: String str = "Hello"; str.concat(" World"); // New string created instead of modifying original.
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Streams api..?factorial using streams

Q1. Difference Between Interface and Abstract Classes?
Ans. 
Interface is a blueprint of a class with only abstract methods, while abstract class can have both abstract and concrete methods.
• Interfaces can only have abstract methods and cannot have any implementation, while abstract classes can have both abstract and concrete methods.

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

• Interfaces are used to achieve multiple inheritance in Java, while ...read more
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Q2. What is indexing in Mysql?
Ans. 
Indexing in MySQL is a way to optimize database queries by creating a data structure that allows for faster retrieval of data.
• Indexes are created on columns in a table to speed up SELECT queries.

• They work similar to an index in a book, allowing the database to quickly find the rows that match a certain value.

• Indexes can be created using the CREATE INDEX statement.

• Examples: CREATE INDEX idx_name ON table_name(column_nam
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Q1. Java 8 related questions with some basic coding using java 8.
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Q2. Print some thing java 8 lambda expression
Ans. 
Using lambda expressions in Java 8 to print a message
• Use the lambda syntax (parameters) -> { body } to define the behavior

• Example: () -> System.out.println("Hello, World!")
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Q1. Project related questions and some coding questions
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Q1. Work Details, education details
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Q1. What is spring boot starters
Ans. 
Spring Boot starters are a set of convenient dependency descriptors that you can include in your application.
• Spring Boot starters provide pre-configured dependencies to simplify the setup of Spring applications.

• They help in reducing the amount of boilerplate code needed to configure common functionalities.

• Examples of Spring Boot starters include spring-boot-starter-web for web applications and spring-boot-starter-data-
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Q2. What is jvm
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JVM stands for Java Virtual Machine, it is an abstract computing machine that enables a computer to run Java programs.
• JVM is responsible for converting Java bytecode into machine code that can be executed by the computer's operating system.

• It provides a runtime environment for Java programs to run in a platform-independent manner.

• JVM manages memory, handles garbage collection, and provides security features for Java ap...read more
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Q1. What is Functional Interface? What is Flat Map? What is Method Reference? What is stream API
Ans. 
Functional Interface is an interface with only one abstract method. Flat Map is used to flatten nested collections. Method Reference is a shorthand notation for lambda expressions. Stream API is used to process collections of objects.
• Functional Interface is an interface with a single abstract method, such as Runnable or Comparator.

• Flat Map is a method in Java that is used to flatten nested collections, like List> ...read more
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Q2. What is Flat Map
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FlatMap is a method in Java that transforms each element of a stream into a new stream and then concatenates all the streams into a single stream.
• FlatMap is used to flatten nested collections or maps into a single collection.

• It is commonly used in Java streams to process and transform data efficiently.

• Example: List> nestedList = Arrays.asList(Arrays.asList(1, 2), Arrays.asList(3, 4)); nestedList.stream().flatMap(L
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Q3. What is Stream API

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Stream API is a feature in Java that allows processing collections of objects in a functional style.

• Stream API provides a way to perform operations on collections like filter, map, reduce, etc.

• It supports functional programming paradigms like lambda expressions and method references.

• Example: List names = Arrays.asList("Alice", "Bob", "Charlie"); Stream stream = names.stream();

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