HSBC Group Lead Java Developer Interview Questions and Answers

Objects of String are stored in the String Pool in Java.

• String objects are stored in the String Pool, a special memory area in Java heap memory.

• String literals are automatically stored in the String Pool.

• String objects created using the new keyword are not stored in the String Pool.

• String.intern() method can be used to store a String object in the String Pool.

A bean in Spring Boot is a Java object that is instantiated, assembled, and managed by the Spring IoC container.

• Beans are defined in the Spring configuration file or using annotations like @Component, @Service, @Repository, etc.

• Beans are singleton by default but can be scoped as prototype, request, session, etc.

• Beans are injected into other beans using dependency injection.

• Example: @Component annotation is used to defi

Query parameters are used to pass data to a web server through the URL, while path parameters are part of the URL itself.

• Query parameters are key-value pairs added to the end of a URL after a '?'

• Path parameters are variables within the URL path itself, denoted by curly braces {}

• Example of query parameter: www.example.com/api/users?id=123

• Example of path parameter: www.example.com/api/users/{userId}

Exceptions are recoverable errors that can be handled in code, while errors are unrecoverable issues that usually result in program termination.

• Exceptions are checked at compile time, while errors are unchecked.

• Exceptions are subclasses of Throwable, while errors are subclasses of Error.

• Examples of exceptions include FileNotFoundException, NullPointerException, while examples of errors include OutOfMemoryError, StackOv

Reverse a string while keeping the position of spaces intact

• Split the string into an array of characters

• Iterate through the array and reverse the characters while keeping track of space positions

• Join the array back into a string

Query param is used to pass parameters in the URL query string, while path param is used to define parameters in the URL path itself.

• Query param is specified after the '?' in the URL, like '?param=value'

• Path param is specified in the URL path itself, like '/{param}'

• Query params are optional and can be used for filtering or sorting data

• Path params are used to define variables in the URL path, like IDs or names

Arrays have fixed size, while ArrayLists can dynamically resize. ArrayLists are part of Java Collections framework.

• Arrays have a fixed size, while ArrayLists can dynamically resize.

• Arrays can hold primitive data types and objects, while ArrayLists can only hold objects.

• Arrays use square brackets [] for declaration, while ArrayLists use angle brackets <>.

• Arrays are faster than ArrayLists for accessing elements directly ...read more

Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

• Abstract class can have constructors, fields, and methods, while interface cannot have any of these.

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

• Abstract classes are used to provide a common base for subclasses, while interfaces are used to define a contract for classes to ...read more

Flatmap implementation in Java is used to transform each element of a stream into a new stream and then concatenate the resulting streams into a single stream.

• Flatmap is a method in Java that takes a function as an argument and applies it to each element of a stream, resulting in a new stream.

• It is commonly used to deal with nested collections or to flatten a collection of collections.

• Example: List> nestedList = A...read more

Answers to common Java Developer interview questions

• 1) Concurrency is achieved using multithreading in Java. Use threads, executors, or synchronized blocks. Example: using ExecutorService to run multiple tasks concurrently.

• 2) Rest API in Springboot: Entity class defines database table, Service class contains business logic, Repository class interacts with database, Controller class handles HTTP requests.

• 3) Volatile key...read more