10+ Principal Software Engineer Interview Questions and Answers for Freshers

Static variables can be accessed from non-static methods using an object reference or by making the variable non-static.

• Static variables can be accessed from non-static methods by creating an object of the class containing the static variable.

• Alternatively, the static variable can be made non-static to be accessed directly from a non-static method.

• Attempting to access a static variable directly from a non-static method will result in a compilation error.

Two objects created - one in the string pool and one in the heap.

• String 'a' is created in the string pool, while String 'b' is created in the heap.

• String pool is a special area in the heap memory where strings are stored to increase reusability and save memory.

• Using 'new' keyword always creates a new object in the heap, even if the content is the same as an existing string in the pool.

Only the original string 'Something' will be garbage collected.

• The concat method in Java does not modify the original string, but instead returns a new string with the concatenated value.

• In this case, 'a' remains as 'Something' and a new string 'Something New' is created, but not assigned to any variable.

• Since the new string is not stored in any variable, it will not be garbage collected.

Merge and remove duplicates from two sorted arrays without using Collections

• Use two pointers to iterate through both arrays simultaneously

• Compare elements at each pointer and add the smaller one to the result array

• Skip duplicates by checking if the current element is equal to the previous element

I use a combination of automation tools and manual checks to ensure smooth deployment process.

• Automate repetitive tasks using tools like Jenkins or Ansible

• Perform manual checks to ensure quality and avoid errors

• Use version control to track changes and roll back if necessary

• Collaborate with development and operations teams to ensure smooth deployment

• Monitor system performance and troubleshoot issues as they arise

Implement LRU Cache using a data structure like LinkedHashMap in Java

• Use LinkedHashMap to maintain insertion order

• Override removeEldestEntry method to limit cache size

• Update the access order on get and put operations

Sorting collections using comparator

• Implement the Comparator interface

• Override the compare() method to define sorting logic

• Pass the comparator object to the sort() method of the collection

• Example: Arrays.sort(arr, new MyComparator())

Creating a deadlock involves two or more threads waiting for each other to release a resource they need.

• Create two threads, each trying to lock two resources in a different order

• Ensure that one thread locks resource A first and then tries to lock resource B, while the other thread locks resource B first and then tries to lock resource A

• This will result in a situation where each thread is waiting for the other to release the resource it needs, causing a deadlock

POJO is a Plain Old Java Object with private fields and public getters/setters, while a Bean is a Java class with private fields and public zero-argument constructors.

• POJO stands for Plain Old Java Object

• POJO has private fields and public getters/setters

• Bean is a Java class with private fields and public zero-argument constructors

• Beans are usually used in Java EE frameworks like Spring for dependency injection

Code to read a file in Java

• Use FileReader and BufferedReader classes to read the file

• Handle exceptions using try-catch blocks

• Close the file after reading using close() method

Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Ensures a class has only one instance by providing a global access point to it.

• Uses a private constructor to restrict instantiation of the class.

• Provides a static method to access the singleton instance.

• Commonly used in scenarios where only one instance of a class is needed, such as database connections or logging.

• Example: Singleton pattern can be implemented in Java using a pr...read more

Angular pipes are used to transform data in templates. Types in Angular provide static type checking.

• Angular pipes are used to format and transform data in templates.

• They can be used to filter, sort, and manipulate data before displaying it.

• Pipes can be chained together to perform multiple transformations.

• Types in Angular provide static type checking and help catch errors during development.

• They ensure that variables and function parameters have the correct data types.

Implement a simple Tic Tac Toe game in code, allowing two players to take turns and check for a winner.

• Use a 2D array to represent the game board, e.g., [['', '', ''], ['', '', ''], ['', '', '']].

• Create a function to display the board after each move.

• Implement a function to check for a win condition (three in a row).

• Allow players to input their moves and validate the input.

• Handle the case of a draw when all cells are filled without a winner.