10+ Oracle Senior Application Developer Interview Questions and Answers

Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraint.

• Implement a doubly linked list to keep track of the order of keys based on their recent usage.

• Use a hashmap to store key-value pairs for quick access and update.

• When capacity is reached, evict the least recently used item before inserting a new item.

• Handle get and put operations efficiently to maintain the LRU property.

• Ensure the time complexity of operations ...read more

Convert a binary tree to a sum tree by replacing each node with the sum of its left and right subtrees, setting leaf nodes to zero.

• Traverse the tree in postorder fashion to calculate the sum of left and right subtrees for each node.

• Set leaf nodes to zero by checking if a node has no children.

• Update the value of each node to be the sum of its left and right subtrees.

• Return the level order traversal of the converted sum tree.

Find the node where two linked lists merge, return -1 if no merging occurs.

• Traverse both lists to find their lengths and the difference in lengths

• Move the pointer of the longer list by the difference in lengths

• Traverse both lists simultaneously until they meet at the merging point

Java is platform independent because it compiles code into bytecode that can run on any system with a JVM, which is platform dependent due to its reliance on the underlying hardware and operating system.

• Java code is compiled into bytecode, which can run on any system with a JVM installed.

• JVM acts as an intermediary between the Java code and the underlying hardware/OS, making it platform dependent.

• The JVM interprets the bytecode and translates it into machine code specific to ...read more

Yes, it is possible to import the same class or package twice in Java, but it will not cause any issues during runtime.

• Importing the same class or package multiple times in Java will not result in any errors or conflicts.

• The Java compiler will simply ignore duplicate imports and only include the class or package once in the compiled code.

• This behavior helps in avoiding unnecessary redundancy and keeps the code clean and concise.

MVC components include Model, View, and Controller for organizing code in a web application.

• Model: Represents the data and business logic of the application.

• View: Represents the UI and presentation layer of the application.

• Controller: Acts as an intermediary between Model and View, handling user input and updating the Model accordingly.

• Example: In a web application, a user interacts with the View (UI), which sends requests to the Controller. The Controller processes the reque...read more

Marker interfaces in Java are interfaces with no methods, used to mark classes for special treatment.

• Marker interfaces have no methods, they simply mark a class as having a certain capability or characteristic.

• Examples of marker interfaces in Java include Serializable, Cloneable, and Remote.

• Classes implementing marker interfaces can be treated differently by the JVM or other components based on the interface they implement.

Routing in MVC pattern is handled by a routing engine which maps incoming URLs to specific controller actions.

• Routing is the process of matching incoming URLs to specific controller actions in the MVC pattern.

• Routes are defined in a routing table which maps URLs to corresponding controller actions.

• The routing engine uses the routing table to determine which controller and action should handle a particular request.

• Routes can include placeholders for dynamic segments of the URL...read more

Filters in MVC are components that allow pre-processing and post-processing of requests and responses.

• Filters are used to perform common functionalities like logging, authentication, authorization, etc.

• They can be applied globally to all controllers or selectively to specific controllers or actions.

• Examples of filters include Authorization filters, Action filters, Result filters, and Exception filters.

Garbage collector in Java is a built-in mechanism that automatically manages memory by reclaiming unused objects.

• Garbage collector runs in the background to identify and delete objects that are no longer needed.

• It helps prevent memory leaks and optimize memory usage.

• Examples of garbage collectors in Java include Serial, Parallel, CMS, and G1.

Railway Reservation System for booking train tickets.

• Users can search for trains based on source and destination stations.

• Users can select preferred train, class, and seat.

• System should handle payment processing and generate e-tickets.

• Admin panel for managing trains, schedules, and bookings.

• Integration with SMS/email notifications for updates.

• Database to store train details, user information, and booking history.

Spring MVC is a framework used for building web applications in Java.

• Spring MVC stands for Model-View-Controller, which is a design pattern for separating concerns in a web application.

• It provides a powerful model for building flexible and loosely coupled web applications.

• It integrates with other Spring frameworks like Spring Boot, Spring Security, and Spring Data.

• It uses annotations to simplify configuration and reduce boilerplate code.

• Example: @Controller annotation is used...read more