humanoid readable – Computer Programming for Humanoids

Don’t use Set.of().contains(). Use switch instead.

Set.of(a, b, c).contains(value) might seem clever and while it is easy to read it’s way slower than switch(x) {case a,b,c -> true}.

We often have to check if a value is one of a given set of values. But we don’t want to write code like this:

if (value == SomeEnum.FOO || value == SomeEnum.BAR || value == SomeEnum.QUX) { ...

Some use a Set and write it like this:

if (Set.of(SomeEnum.FOO, SomeEnum.BAR, SomeEnum.QUX).contains(value)) { ...

But now the runtime has to create a Set each time this line is run and it also has to call the method contains. And it can’t even handle null. In Java we have a much better alternative: The switch expression. You can use it like so:

if (switch (value) { case FOO, BAR, QUX -> true; default -> false; }) { ...

@SafeVarargs and Heap Pollution

When should we use this annotation? How can we prevent heap pollution?

No, ChatGPT can’t replace human programmers

ChatGPT and other bots aren’t even general artificial intelligence. Those who claim they could replace human programmers are wrong or lying.

ChatGPT and other bots aren’t even general artificial intelligence. They don’t understand anything. Some people are now pushing the misconception that the large language models we have now are already AI and can replace human workers.

Rotate BufferedImage in Java

Simple method that correctly rotates a BufferedImage.

Java code to easily rotate a buffered image.

It’s about RTFM, not BOMDAS!

Different results can both be correct. This depends on the grammar used to parse the expression. Some handle implied multiplication with higher precedence, others don’t.

There’s this meme on the internet about two calculators (or phone calculator apps) with different results. This is a common misconception and therefore a perfect topic for my blog.

My first inline class for Java

I’ve once made a simple helper class for a set of bytes stored as an integer bitfield. So the idea is that each of the 32bits is used to represent if the ordinal number is in the set or not. This only works for the bytes 0 to 31.
Now this is an “inline class” – something we will get with Project Valhalla.
Here’s the branch of my project:
https://github.com/claudemartin/smallset/tree/valhalla

For this to work you need a JDK with a preview of Project Valhalla. Check java.net for that: http://jdk.java.net/valhalla/

Just download that JDK, clone my branch, build using Ant, and see what you can do with it. It’s actually a good example of an inline class, because it is just an integer (primitive) value but has methods (like a referenced type would). It doesn’t need object identity, but should still behave like an object. For example the sets are comparable. The type actually implements the Comparable interface.

Note that this might not work with newer JDKs. I used JDK 14 + valhalla from java.net and the feature might look quite different in newer releases of Java.

Streamed SQL

I just saw that I never posted this here on my blog. JDBC is still a good way to just connect to some SQL database where JPA would be overkill. So I wrote a library that allows you to use the Java Stream API to process that data.

The Code is on GitHub:

https://github.com/claudemartin/streamed-sql

Example Code:

Connection conn = dbpool.getConnection();
var strsql = StreamedSQL.create(conn, true); 
try (Stream<Foo> stream = strsql.stream("SELECT * FROM FOO", Foo::new)) {
  stream.filter(f -> f.getName().startsWith("L")).sorted().forEachOrdered(System.out::println);
}

WeakAssQueue

LIFO queue that will drop old elements when needed.

The Idea

Have a Last-In-First-Out queue (implements java.util.Queue<E>) that will release old elements so that garbage collection (GC) can remove them. Like a cache that is a stack.

Java Assignments are evaluated Left to Right

I think I’ve just found a mistake in the Java Tutorial.

Maybe I’m just being pedantic, but I think I’ve just found a mistake in the Java Tutorial. It claims:

All binary operators except for the assignment operators are evaluated from left to right; assignment operators are evaluated right to left.
The Java™ Tutorials » Language Basics » Operators

What is this supposed to mean? Evaluation from right to left would mean that when you have a line like the following you get the rightmost expression evaluated first:

int x = 42;
x += getNumber();
// The above would be equivalent to:
x = getNumber() + x;

But that’s not how Java actually evaluates this expression. And the JLS 12 (2019-02-08) clearly states in 15.26.2 that “the value of the left-hand operand is saved and then the right-hand operand is evaluated.”

Using WSL from Java

With Windows Subsystem for Linux (WSL) we can now use Linux tools, such as grep, rsync, ssh, and network commands, such as dig and netstat, on Windows directly. No need for cygwin or other 3rd party software.

Here’s an example on how uname is unknown to Windows, but WSL (Ubuntu in my case) knows it: