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Sometimes when I run my app I get a similar error: Exception in thread "main" java.lang.NullPointerException at com.e ... cing. Translation of the question: "What is a stack trace, and how can I use it to debug my application errors?" @Rob Hruska

What is interning? What is it used for? When should it be used and what possible pitfalls?

The answers to this question were written by the joint efforts of the community. To improve this message, edit the existing r ... he general answer. This list is included in the community-supported Collection of educational resources on programming.

Hello! I ask this question more for self-education than out of a real momentary need: What do "higher-level" programmers ne ... of a number without a comparison operation Do bitwise operators (other than shifts) make any mathematical sense in base-10?

As Albert Einstein said: If you can't explain something to a six-year-old, I don't think you quite understand it yourself. ... sures (functions, variables, scope, etc.), except, in fact, closures? This question is translated from English-language SO.

Inspired by the article about the differences between DTO, POCO and Value Object on Habrahabr: DTO vs POCO vs Value Object, a ... ack of that fine line "what's in the POCO, what's in the service" or in general "all the logic in the services, operate DTO"?

Как работает оператор проверки на равенство (оператор ==)? Имеются ли ему альтернативы? Если альтернативы имеются, то в каких ситуациях следует их применять?

What are the differences between an abstract class and an interface?

I looked through a lot of links in Google, but still did not get a specific answer: what task does the Greenrobot EventBus li ... s to use them), unless it makes sense to use the library in communication between Service and other parts of the application.

There is often a need to work with Json, in particular its reading and parsing. In Java, you usually know what type of variab ... "type": "home", "number": "999 111-1234" } ] } ] }

What does "@Override" mean before declaring a method?

Прочел в документации и нигде не нашел объяснения (гуглил без результата), почему для реализации сортиров ... k7/tl/jdk/rev/bfd7abda8f79 Обещают замечательные характеристики (по дополнительной памяти max n/2 !) и вообще интересно.

In my program, I used the == operator to compare strings. But I came across a bug, and when replacing == with equals, it disappeared. Should the == operator be avoided? When can it be used and when not? What's the difference?

This question is already answered here: ... l. Can you tell me where to start and where to read about it? Thank you in advance :) P.S. preferably with practical examples

It's just written differently everywhere. And I can not understand what each of these concepts actually means. For example, t ... other threads to enter this code block). Is this the correct understanding? And what exactly do these concepts mean in Java?

Во многих языках программирования (C, C++, C#, Java, различные диалекты Паскаля, PHP, Javascript) есть оп ... 0 = 0 * 3 + 0 -1 / 3 == -1 -1 % 3 == 2 -1 = -1 * 3 + 2 -2 / 3 == -1 -2 % 3 == 1 -2 = -1 * 3 + 1 И т. д.

What is the difference between LinkedList and ArrayList? And in what cases is it more convenient to use LinkedList in practice?

Is there a library implementation of translating sums into words in Russian? If not, how to implement it in the optimal way?

Explain the difference between: Component, Repository, Service in the Java Spring Framework. Give simple usage examples.

Решил написать простенькую телепрограмму с использованием jsoup. Задача более чем скучная, но для меня н ... спарсить расписание с первого канала на странице. И может быть вы считаете, что jsoup полная лажа посоветуйте другой.