Groovy 2.5.0 makes it possible to get the location of a Class file by adding the method getLocation to the Class class. If the Class is part of the JDK the location returned is null, but otherwise we get the location of the JAR file or source file (if available) with the Class file.

In the following example we get the location for the internal JDK String class and the Groovy utility class ConfigSlurper:

Groovy adds a lot of useful methods to the String class. Since Groovy 2.5.0 we can even calculate MD5 and SHA hash values using the methods md5 and digest. The md5 method create a hash value using the MD5 algorithm. The digest method accepts the name of the algorithm as value. These values are dependent on the available algorithms on our Java platform. For example the algorithms MD2, MD5, SHA-1, SHA-256, SHA-384 and SHA-512 are by default available.

In the next example we use the md5 and digest methods on a String value:

Groovy 2.5.0 adds several methods to make working with Java 8 Streams more Groovy. First of all the methods toList and toSet are added to the Stream class. These methods will convert the stream to a List and Set using the Stream.collect method with Collectors.toList and Collectors.toSet as argument. Furthermore we can convert any array object to a Stream using the stream method that is added to all array objects.

In the following example we use the support of converting an array to a Stream and then getting a List and Set from the stream:

In Groovy 2.5.0 we can use a Java 8 Optional object in a conditional context. When an Optional object has a value the value is coerced to true and when empty the value is false.

Written with Groovy 2.5.0.

We can use ranges in Groovy using an easy syntax where the start and end values of the range are separated by .. for an inclusive range and ..< for an exclusive range as we have seen in a previous post. The values of the range are mostly numbers or enum values. But we can also use String values to define a range. Groovy will check if the String values are the same length and if the values, except for the last character, are the same. Then the natural ordering of the last character of the String value, based on the character’s int value, is used to create the range values.

In the following example we define several ranges using String values. We can even define a reverse range using String values.

Groovy has support for defining ranges in the language. When we define a range of numbers the steps between the values in the range is 1 by default. We can change the step size using the step method. This method accepts a int value with a new step size. The result is a List object with the values. Since Groovy 2.5.0 the by method is added to ranges with numbers. The by method accepts also decimal numbers and the result of the method is a NumberRange object instead of a List.

In the following example Groovy script we first define a range with int values. We use the by method to change the step size using both an int value and BigDecimal value. We also use the by method for a range of BigDecimal numbers:

PlantUML mostly does a good job organizing elements and arrows in the resulting diagram. But we can help PlantUML by defining the arrow direction in our PlantUML definition. We can use the keywords up, down, left and right inside the arrow definition.

In the following example we have five rectangles connected with arrows. We define the arrow direction for each arrow.

One of the command line options of Gradle is --offline. With this option we run Gradle in offline mode to indicate we are not connected to network resources like the internet. This could be useful for example if we have defined dependencies in our build script that come from a remote repository, but we cannot access the remote repository, and we still want to run the build. Gradle will use the locally cached dependencies, without checking the remote repository. New dependencies, not already cached, cannot be downloaded of course, so in that scenario we still need a network connection.

We can check in our build script if the --offline command line argument is used. We can use this to disable tasks that depend on network resources so the build will not fail. To see if we invoked our build with the --offline option we can access the property gradle.startParameter.offline. The value is true if the command line argument --offline is used and false if the command line argument is not used.

Gradle added an incubation feature to Gradle 4.6 to add command line options for custom tasks. This means we can run a task using Gradle and add command line options to pass information to the task. Without this feature we would have to use project properties passed via the -P or --project-property. The good thing about the new feature is that the Gradle help task displays extra information about the command line options supported by a custom task.

To add a command line option we simply use the @Option annotation on the setter method of a task property. We must make sure the argument for the setter method is either a boolean, Boolean, String, enum, List<String> or List<enum>. The @Option annotation requires an option argument with the name of the option as it must be entered by the user. Optionally we can add a description property with a description about the option. It is good to add the description, because the help task of Gradle displays this information and helps the user of our custom task.

In our Groovy scripts we can use the @Grab annotation. With this annotation we define dependencies for our script and they will be automatically downloaded and added to the class path when we run our script. When we use IntelliJ IDEA we can use a nice intention that is part of the IntelliJ IDEA Groovy support to download the dependencies from our IDE editor. IDEA downloads the dependencies and add it to the project module dependencies. This is useful, because this will also adds code completion for the classes in the dependency to our editor.

Let’s see this with a little example. We have the following Groovy script in our Groovy project in IntelliJ IDEA:

Just as we are over the crest of the microservice hype and can finally see how this architectural tool might (or might not) solve our problems the next hype is already here: serverless programming! In this first blog post I’m going to explain what serverless is, what it isn’t, and how it can change the way we create software. In the next posts I’m going to show a few simple examples using a well known 'serverless' platform: AWS Lambda. Originally posted here .

PlantUML has a built-in icon set we can use in our diagram definitions. The icon set is open source icon set OpenIconic. We refer to an icon using the syntax <&iconName>.We can use an icon everywhere where we can use text in our diagrams.

In the following example we use different icons in different places: