Articles

Hi! In previous lessons, we've already briefly become acquainted with the concept of inheritance. Today, we'll touch on this topic again, but again not too deeply. We are still going to have a more detailed lesson on this in the future. Today we'll just take a quick look at a few practical examples and get ...

Hi! You're already familiar with the word "modifier". At a minimum, you've encountered access modifiers (public, private) and the static modifier. Today we'll discuss a special modifier called final. You could say the final modifier "cements" parts of our program where constant, unambiguous, unchanging behaviors ...

Hi! As you have progressed through CodeGym, you've encountered primitive types many times. Here is a short list of what we know about them: they are not objects and represent a value stored in memory, there are several kinds, each type has its own range of values ...

Hi! In the last lesson, we got acquainted with exceptions in the Java language, and saw examples of how to work with them. Today we will take a deeper look at the structure of exceptions, and learn how to write our own exceptions. :) As we said previously, there are a lot of exceptions in Java, almost 400 ...

Hi! I hate to mention it, but a huge part of a programmer's work is dealing with errors. Most often, his or her own. It turns out that there are no people who don't make mistakes. And there are no such programs either. Of course, when dealing with an error, the main thing is to understand its cause ...

Hi! You've already known about creating your own classes with fields and methods. Now we'll dwell on methods. Of course, we've already done this more than once in our lessons, but we've mainly covered generalities. Today, we're going to dissect methods, and study what they're made of ...

Hi! Today we'll start working with a new data type we haven't encountered before, namely, dates. I don't think I need to explain what a date is. :) In principle, we could store the current date and time in an ordinary Java String. But this approach has many drawbacks. The String class is designed to work with text ...

Hi! Previously, we've studied data structures where the elements are stored as themselves. In an array or an ArrayList/LinkedList, we store some number of elements. But what if our task changes a little? Imagine the following task: create a list of 100 people that stores each person's name and passport number ...

Hi! All the latest lessons have been devoted to ArrayList. This data structure is very convenient and useful. It can handle plenty of tasks. But Java has lots of other data structures. Why? Above all, because the range of tasks is enormous, and the most efficient data structures are different for different tasks ...

Hi! In the past few lessons, we've made great progress in our mastery of ArrayList. However, so far we've only performed the simplest operations: remove, insert, and display. Of course, this doesn't cover the full list of tasks that developers must perform when working with ArrayList ...

Hi! Today's lesson about ArrayList will be both easier and harder than previous lessons. It will be more difficult because today we're going to look under the hood of ArrayList and study what happens during various operations. On the other hand, this lesson will have almost no code ...