John Selawsky Senior Java Developer and Tutor at LearningTree
A senior Java developer and Java tutor at Learning Tree International programming courses. Sometimes I write some stupid programming stuff about Java.
7 years experience of Java/J2EE development. In Java We Trust.
Author's articles
- 8 June 2021 5:14Java Byte KeywordWhat is a “byte”? 8 bits (bit is the smallest unit of data containing at most 2 logical states, normally 0 and 1) combine to make a single unit of addressable memory, called a “Byte”. Here’s a theoretical representation of what a byte normally looks like...
08.06.2021 5828views 0comments
2 - 18 November 2020 11:06HashSet contains() Method in JavaWhat is a HashSet? HashSet is a built-in datatype in Java, and in layman terms you can say “HashSet is an unordered collection of unique elements.” Have a look at a basic example. HashSet extends (extends means a class is inherited from another class) AbstractSet and...
18.11.2020 8011views 0comments
4 - 13 May 2020 12:36Using varargs when working with genericsHi! In today's lesson, we'll continue to study generics. As it happens, this is a big topic, but there's no avoiding it — it's an extremely important part of the language :) When you study the Oracle documentation on generics or read online tutorials, you will come across the terms non-reifiable types and reifiable types...
13.05.2020 4487views 0comments
17 - 26 March 2020 7:43Nested inner classesHi! Today we'll take up an important topic: how nested classes work in Java. These internal classes are called nested. They are divided into 2 types: Non-static nested classes (these are also called inner classes), Static nested classes. In turn, inner classes have two distinct subcategories...
26.03.2020 6048views 3comments
40 - 26 March 2020 6:55Anonymous classesHi! In today's lesson, we'll continue to examine the topic of nested classes. Now it's time for the last group: anonymous inner classes. Like the local classes that we talked about in the last lesson, anonymous classes are a kind of inner class... They also have several similarities and differences...
26.03.2020 5189views 3comments
44 - 16 January 2020 9:41Static nested classesHi! We continue to explore the topic of nested classes in Java. In the last exercise, we spoke about non-static nested classes, which are also known as inner classes. Today we move on to another group of classes. We'll consider static nested classes. How are they different from other classes?
16.01.2020 4265views 1comment
31 - 4 September 2019 9:258 common mistakes made by rookie programmersHi! Today we'll look at 8 very common mistakes made by rookie (and other) Java developers. You'll find plenty of such lists on the web: many of them are similar to one another. As we compiled our list, we were guided by one criterion: whether we made the mistakes ourselves during our studies or employment...
04.09.2019 14207views 20comments
184 - 23 July 2019 13:01BufferedReader and BufferedWriterJava’s BufferedReader class reads text from a stream of symbols, buffering the symbols to efficiently read characters, arrays, and strings. You can pass the buffer size to the constructor as a second argument. Here's an example of using the BufferedReader and BufferedWriter classes...
23.07.2019 23005views 1comment
16 - 20 March 2019 12:15Widening and narrowing of reference typesHi! In a past lesson, we discussed casting primitive types. Let's briefly recall what was discussed. We imagined primitive types (in this case, numeric types) as nesting dolls that vary in size according to the amount of memory they occupy...
20.03.2019 12513views 24comments
147 - 19 July 2018 12:04Object lifecycle Hi! I think you wouldn't be very surprised if I told you that your computer has a limited amount of memory :) Even your hard drive (which is many, many times the size of RAM) can get chock full of your favorite games, TV shows, and other things. To prevent this from happening, you need to monitor the current state ...
19.07.2018 34773views 43comments
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