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Author Archives: Vadim Korkin

Vadim is a senior software engineer with lots of experience with different software technologies including Java, Javascript, databases (Oracle and Postgres), HTML/CSS and even machine learning. He likes learning new technologies and using the latest libraries in his work. Vadim also has some personal projects on Github

Antlr 4 grammar with spaces

Intro This post discusses the difficulties and solutions of creating an Antlr grammar without removing spaces from the text being parsed. But first, a brief explanation of what Antlr really is. Here is the link https://github.com/antlr/antlr4. Antlr can take a text with a well-defined rules and create a syntax tree out of it. It is basically what it is so good ...

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Flexible Styling with Varying Criteria for POI-created documents

Intro This post explains the difficulties with applying styles to a document based on varying criteria and offers a solution. One of the common tasks in Java programming is to create an Excel report from data that is stored in the database. In these cases, Java programmers use POI :-).  These reports often have strict rules for styling and data ...

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Insert content with Apache POI

Intro Everybody knows POI! It is the best library available to create Excel documents in Java. it is really good and can do a lot of things easily. But recently I wanted to do something not so simple. I wanted to use an existing xlsx file as a template and insert some data into it at some position. In this ...

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Spring Custom Serializers with @JsonIdentityInfo

spring-interview-questions-answers

Intro Serialization/Deserialization from/to JSON in Spring is widely used in modern Spring-based applications. It is based on Jackson. Jackson can serialize any POJO into JSON and vice versa with ease. This code is well written. I never encountered any issues. It gets more difficult when custom serializers are involved. This post shows how to use custom serializers in Spring with ...

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Spring Data with Thymeleaf

spring-interview-questions-answers

Intro Today I’ll talk about more specific issues. No design patterns or algorithms this time :-). We don’t always design software components from scratch. Often we have to try to make existing software components work together. Spring Boot is one the best free software in the Java world. It resolved a lot of configuration issues with Spring. It is very ...

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Eclipse RAP with Spring Boot

Intro I like Eclipse :-). I’ve been using it for many years. I think the IDE is great and it is free! But Eclipse is much more than just the IDE. It is more like an ecosystem of applications, plugins and projects. Anyone can use the Eclipse Framework to create his/her own Eclipse-based application.   It is called Eclipse RCP ...

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Multilevel Adapter Pattern

Intro This post continues my “new pattern ideas” series. I’ll describe a special version of the adapter pattern that can guarantee several levels of access to objects. In particular I’ll show 3 main levels – read, write and class access. Motivation We’ll consider a 2-tiered system: The top tier consists of object folders. Every folder contains objects of one type ...

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Search for time interval in logs

java-interview-questions-answers

Intro This post is indirectly related to my mini-series about log analysis. It would be great to read the two main parts to better understand what I’m talking about. Part 1, Part 2. This post describes one important problem I ran into while implementing the IDE approach. Task Description When someone is working with logs usually he or she needs to investigate ...

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IDE approach to log analysis pt. 2

java-interview-questions-answers

Intro In the first part I explained the theoretical approach to log analysis that I think is best for a sustain engineer. This engineer doesn’t need to analyze logs immediately as they come but instead is focused on a deep analysis of complicated issues. In this second part I’ll show that many search scenarios can be covered with one sophisticated template and ...

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