Getting Started with Gradle

Create a new Gradle Project with IntelliJ IDEA

1. On the welcome screen, click New Project.

   

2. On the page that opens, let's specify our project's name (FizzBuzz) and the location.

3. Let's select the Java option, which is what we need for our project and Gradle since we are creating a Gradle project.

4. IntelliJ IDEA automatically adds a project SDK (JDK) in the JDK field. In our tutorial we use the open JDK 14 version.

   You can change the selected JDK, IntelliJ IDEA will download the appropriate Gradle version. The only thing you need to have is the internet connection.

   Let's leave the default Groovy for Gradle DSL and unselect the Add sample code option since we're going to add our own code from scratch.

5. We can use the default information for ArtifactId which basically is the name of our project and leave the default information in the GroupId field.

   Click Create.

Add a Java class to the Gradle project

1. In the Project tool window open the src folder.

2. Click the main directory then right-click the java subdirectory and from the list select New | Package.

3. In the New Package dialog, let's enter a name of our package which is com.gradle.tutorial.

4. Now right-click the package and select New | Java Class.

5. In the New Java Class dialog specify a name of your Java class and click OK. In our case it is FizzBuzzProcessor.

   

6. Add the following code to the main FizzBuzzProcessor class:

   package com.gradle.tutorial; public class FizzBuzzProcessor { public static void main(String[] args) { for (int i = 1; i <= 100; i++) { System.out.println(convert(i)); } } public static String convert(int fizzBuzz) { if (fizzBuzz % 15 == 0) { return "FizzBuzz"; } if (fizzBuzz % 3 == 0) { return "Fizz"; } if (fizzBuzz % 5 == 0) { return "Buzz"; } return String.valueOf(fizzBuzz); } }

Create a test class

1. Open the main class FizzBuzzProcessor in the editor, place the caret at the class name and press Control+Shift+T.

2. In the dialog that opens, let's make sure that our testing library is JUnit4 (if you want to use JUnit5 then make sure you have the JUnit5) and the destination package is com.gradle.tutorial. We add the name FizzBuzzTest and leave the rest of the default options as is and click OK.

3. Now open the created test class and add the following code:

   package com.gradle.tutorial; import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.Test; import static org.junit.jupiter.api.Assertions.*; public class FizzBuzzTest { @Test public void FizzBuzzNormalNumbers() { FizzBuzzProcessor fb = new FizzBuzzProcessor(); Assertions.assertEquals("1", fb.convert(1)); Assertions.assertEquals("2", fb.convert(2)); } @Test public void FizzBuzzThreeNumbers() { FizzBuzzProcessor fb = new FizzBuzzProcessor(); Assertions.assertEquals("Fizz", fb.convert(3)); } @Test public void FizzBuzzFiveNumbers() { FizzBuzzProcessor fb = new FizzBuzzProcessor(); Assertions.assertEquals("Buzz", fb.convert(5)); } @Test public void FizzBuzzThreeAndFiveNumbers() { FizzBuzzProcessor fb = new FizzBuzzProcessor(); Assertions.assertEquals("Buzz", fb.convert(5)); } }

Run main class from the editor

1. Open the main class FizzBuzzProcessor in the editor.

2. In the gutter, click and select Run 'FizzBuzzProcessor.main()'.

   

3. Check the result in the Run tool window.

   

Run tests in a Gradle project

We can run our test from the editor or from the Gradle tool window using the test task. We will use the editor.

• Click in the gutter of the editor.

  

The result of the test will be displayed in the Run tool window.

If we change the default number in one of the tests, it will fail.

As you can see, the Run tool window displays information obout the failed test including the specific line of the code where the error occurred.

1. In the Project tool window, double-click the build.gradle file to open it in the editor.

2. Add the following code:

   jar { manifest { attributes "Main-Class": "com.gradle.tutorial.FizzBuzzProcessor" } from { configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) } } }

3. Click in the editor to load the changes to your project.

4. In the Gradle tool window, open the project's node, then the Tasks node and double-click the build task to run it.

   

   IntelliJ IDEA creates the build directory that contains our JAR file.

   

   You can run the created JAR file in the command line with java -jar command.

5. Check the Run tool window for the results.

   

   Note that the build task includes the test task that Gradle executes. So, if we make a mistake in one of our tests, the test task will fail and the build task will fail as well.

   

Run the JAR file

1. In the Project tool window, double-click the build.gradle file to open it in the editor.

2. Let's add id 'application' to the plugins section and the following code:

   application { mainClassName = 'com.gradle.tutorial.FizzBuzzProcessor' }

3. Click in the editor to load the changes to your project.

4. In the Gradle tool window, open the project's node, then the Tasks node. We can see that Gradle added the distribution node. Open the node and double-click the assembleDist task to run it.

   If we check the build directory now, we'll see that IntelliJ IDEA created additional directories.

   

5. In the Gradle tool window, click on the toolbar.

6. In the window that opens, enter the gradlew run command.

   

   We should have the same result as when we ran the application in the IntelliJ IDEA editor.

   

   Alternatively, you can execute the run task under the application node.