recent posts related to java, jdbc, spring, etc.

A Java method to determine if an integer is between a range

Last night I was writing some code for my Android football game, and decided it would be best if I had a between method, so I could write some code like this to show that I wanted to test to see if a number was between an integer range:

if (between(distance, 8, 10)) { ...

That could would be interpreted as, “If the distance is between the values 8 and 10, do whatever is in the code block.” (I can make that code more readable in Scala, but in Java I think that’s the best I can do.)

How do I round a float or double to an integer in Java?

Java math FAQ: How do I round a float or double to an integer in Java?

Solution: Use Math.round() to round a float (or double) to the nearest integer (int) in Java.

You can see how this works in the examples that follow, where the result is shown in the comment after each line:

A custom JavaFX web browser (to show stock quotes)

I’m currently doing something completely different, and writing a little custom web browser using JavaFX and its WebView component. I’m using it so I can easily look at stock quotes and charts. I just started on it, and the current UI looks like this:

A custom JavaFX WebView web browser

An Easy Rules example (a Java “rules engine”)

I’m considering using Easy Rules as a simple “rules engine” in my Android Football Game application, primarily because (a) there are a ton of “rules” involved in having the computer call offensive and defensive plays, and (b) I’m trying to find a way to simplify that code and make it more maintainable.

The Easy Rules website has a Hello, world demo you can look at to get started, but after that, here is my example.

How to delete a file from a Java Jar file (use zip)

Java Jar file FAQ: Is there an easy way to delete a file from a Jar file?

Yes. Because a Jar file is just a Zip file, you can use the zip command to remove a file from a Jar file, like this:

zip -d MyApp.jar

Of course the file to delete can be any sort of file. I just went through this process where I had to delete a configuration file, and my command looked like this:

How to populate static, predefined data in a Map/HashMap in Java alvin May 13, 2015 - 9:41am

Java FAQ: How do I populate (initialize) a static HashMap in Java?

If you need to initialize/populate a Map/HashMap in Java, the following source code shows the proper syntax: