10+ Deutsche Telekom Interview Questions and Answers

API to get logs of a Spring Boot app in Kibana way, reading from the back.

• Use Spring Boot Actuator to expose endpoints for log retrieval

• Configure Logstash to read logs from the application and send to Elasticsearch

• Use Kibana to visualize and search logs

• Implement pagination to read logs from the back

Use Java 8 Stream API to find the largest number in an array of strings without using additional data structures or loops.

• Convert the array of strings to a stream of integers using map() and parseInt()

• Use reduce() with Math::max to find the largest number in the stream

Permutations of an array of strings are all possible arrangements of the elements.

• Use recursion to generate all permutations.

• Swap elements to create different permutations.

• Base case: when only one element is left, add the permutation to the result.

• Example: Array ['A', 'B', 'C'] has permutations ['ABC', 'ACB', 'BAC', 'BCA', 'CBA', 'CAB'].

Exceptions encountered during automation testing can include element not found, timeout, invalid input, etc.

• ElementNotVisibleException: When an element is present in the DOM but not visible on the page

• TimeoutException: When a command takes longer than the timeout specified

• NoSuchElementException: When an element could not be found in the DOM

• StaleElementReferenceException: When an element is no longer attached to the DOM

• InvalidInputException: When invalid input is provided to a...read more

Java program to reverse a string

• Create a char array from the input string

• Use two pointers to swap characters from start and end of the array

• Convert the char array back to a string and return

Design a car rental platform like ZoomCar.

• Create a user-friendly website and mobile app for booking cars.

• Integrate GPS and other technologies for easy tracking and navigation.

• Offer a wide range of cars for rent, from hatchbacks to luxury cars.

• Provide flexible rental options, including hourly, daily, and weekly rentals.

• Implement a secure payment gateway for hassle-free transactions.

• Ensure proper maintenance and cleaning of cars before and after each rental.

• Offer 24/7 customer ...read more

Parallel stream allows processing elements concurrently, while stream processes elements sequentially.

• Parallel stream can improve performance by utilizing multiple threads for processing.

• Stream processes elements one by one in a sequential manner.

• Example: stream().parallel() vs stream().sequential()

API error codes are numerical or alphanumeric codes that indicate the type of error that occurred during an API request.

• API error codes help developers identify and troubleshoot issues with their API requests.

• Common API error codes include 400 Bad Request, 401 Unauthorized, 404 Not Found, 500 Internal Server Error.

• Each API error code has a specific meaning and can provide valuable information for debugging.

I have extensive experience with various mobile devices, including smartphones, tablets, and wearables.

• Proficient in using both iOS and Android devices

• Familiar with troubleshooting common issues on mobile devices

• Experience in testing mobile apps on different devices and platforms

JDK is a development kit that includes JRE and tools for developing Java applications. JRE is a runtime environment for executing Java programs. JVM is a virtual machine that runs Java bytecode.

• JDK (Java Development Kit) includes JRE (Java Runtime Environment) and development tools like compiler and debugger.

• JRE (Java Runtime Environment) is a software package that provides the libraries and components necessary for running Java applications.

• JVM (Java Virtual Machine) is an a...read more

Final keyword is used in Java to declare constants, prevent method overriding, and prevent class inheritance.

• Used to declare constants - value cannot be changed once assigned

• Prevents method overriding - method cannot be overridden in child classes

• Prevents class inheritance - class cannot be extended

Streams are used in Java to process collections of objects in a functional style.

• Streams allow for concise and readable code when working with collections.

• They support operations like filter, map, reduce, and collect.

• Streams can be sequential or parallel, depending on the processing requirements.

• Example: List names = Arrays.asList("Alice", "Bob", "Charlie"); names.stream().filter(name -> name.startsWith("A")).forEach(System.out::println);

Static variables are shared among all instances of a class, while volatile variables are used to indicate that a variable's value will be modified by different threads.

• Static variables are initialized only once at the start of the program and retain their value throughout the program's execution.

• Volatile variables are used to ensure visibility of changes to variables across multiple threads.

• Static variables are accessed using the class name, while volatile variables are acces...read more

Types of Dispatchers in Android include Main, IO, Default, and Unconfined.

• Main Dispatcher: Handles UI-related tasks and runs on the main thread.

• IO Dispatcher: Handles IO-related tasks such as network or disk operations.

• Default Dispatcher: Used for CPU-intensive tasks that don't block the main thread.

• Unconfined Dispatcher: Executes the coroutine in the caller thread until the first suspension point.

MVVM focuses on separation of concerns, with ViewModel acting as a mediator between Model and View. MVC has tighter coupling between Model, View, and Controller.

• MVVM separates concerns by introducing a ViewModel layer to handle presentation logic.

• MVC has a tighter coupling between Model, View, and Controller, leading to potential code duplication and difficulty in testing.

• In MVVM, the ViewModel exposes data and actions to the View through data binding, reducing the need for c...read more

Troubleshooting involves identifying, isolating, and resolving technical issues to ensure smooth operation of applications.

• Identify the issue by gathering information from users or logs

• Isolate the problem by testing different components or configurations

• Resolve the issue by applying fixes or workarounds

• Document the troubleshooting process for future reference