JVM-languages – Seite 2 – Karl Brodowsky's IT-Blog

Exceptions to implement Program Logic

Sometimes it is conveniant to use exceptions for implementing the regular program logic. Assuming we want to find some data and then process them. When no data is found, this step can be skipped, because there is nothing to do. So we could program something like this: public Data readData(Param param) { Data data = db.read(param); if (data.isEmpty()) { throw new NotFoundException(„nothing found“); } return data; } public ProcessedData doWork(Param param) { …

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Guava-Collections in Java-APIs

When we write APIs, that have parameters or as return values, it is a good idea to consider relying on immutable objects only. This applies also when collections are involved directly or indirectly as content of the classes that occur as return values or parameters. Changing what is given through the API in either direction …

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Scala Days 2019

Scala Days had a tenth anniversary in 2019. It is an annual conference about Scala, which I like to visit, when possible. There is some confusion as to what is meant: Where this the 9th, 10th or 11th Scala Days? Where the first Scala Days 9, 10 or 11 years ago? The truth is, that …

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hashCode, equals and toString

In many programming languages we are urged to define methods hashCode, equals and toString. They are named like this in Java and in many JVM languages or they use similar names. Some languages like Perl and Scala provide decent mechanisms for the language to figure these out itself, which we do most of the time …

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Indexing of Arrays and Lists

We index arrays with integers. Lists also, at least the ones that allow random access. And sizes of collections are also integers. This allows for entries in Java and typical JVM languages, because integers are actually considered to be 32bit. Actually we could think of one more entry, using indices , but then we would …

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Devoxx Kiew 2018

In the end of 2018 the number of conferences is kind of high. A great highlight is the Devoxx BE in Antwerp. But it has now five partner conferences in London, Paris, Krakow, Morocco and Kiev. So I decided to have a look at the one in Kiev. How was it in comparison to the …

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Devoxx Antwerp 2018

In 2018 I am visiting a few conferences. A great highlight is the Devoxx BE in Antwerp, which I had the privilege of visiting 2012, 2013, 2014, 2015, 2016 and 2017. As it should be, it is not just the same every year, but content and speakers change a bit from year to year. Some …

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Logging

Deutsch Software often contains a logging functionality. Usually entries one or sometimes multiple lines are appended to a file, written to syslog or to stdout, from where they are redirected into a file. They are telling us something about what the software is doing. Usually we can ignore all of it, but as soon as …

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Some thoughts about String equality

Of course Strings are today in some way Unicode. In this article we assume code points as the building blocks of Strings. That means for example in the Java-world, that we are talking about one code point being comprised of one Java character for typical European languages, using Latin, Greek or Cyrillic alphabets including extensions …

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Meaningless Whitespace in Textfiles

We use different file formats that are more or less tolerant to certain changes. Most well known is white space in text files. In some programming languages white space (space, newline, carriage return, form feed, tabulator, vertical tab) has no meaning, as long as any whitespace is present. Examples for this are Java, Perl, Lisp …

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