In the first episode of IntelliJ IDEA Tech Talks, I talk to Moritz Halbritter from the Spring team about JSpecify.
We talk about what JSpecify is, and Moritz shows us how to add JSpecify to a codebase. We had a lot of fun recording this episode; I hope you will enjoy the recording!
Description
Null pointer exceptions have been called the billion dollar mistake. They are a common source of bugs and frustration. JSpecify aims to fix that, and with Spring Boot 4 and Spring Framework 7 now fully on board, it’s time to take a closer look. In this episode, Moritz Halbritter from the Spring team walks us through what this means for your Spring projects and how to adopt JSpecify in practice. Using a live demo, we migrate an existing Spring Boot application, tackling problems along the way. See how to use JSpecify for the contract, IntelliJ IDEA for the developer experience, Spring for the framework, and NullAway for the build guarantee. Whether you’re maintaining a large codebase or publishing a library, this episode gives you the tools to start eliminating null pointer exceptions in your applications.
How many shortcuts can you remember? Three? Five? More? I try to learn as many as I can and still forget some of them…
What if you could unlock IntelliJ IDEA features, without having to remember shortcuts? You can still use shortcuts if you want. But you don’t haveto.
Command completion (..) is a new feature in IntelliJ IDEA that lets you discover and execute IDE actions right from your editor.
Command completion extends regular completion
Command completion is an extension of regular code completion – something every developer already uses. For example, when you have a variable, you can type a dot to show you completion options. It will show you API completion (all of the methods you can call on this variable), and postfix completion (templates you can apply to this variable). The list now also includes commands; all relevant commands for your current context. Code completion (a single dot) is now a universal entry point for all relevant actions.
To filter the list to show commands only, type two dots ... As the list can be quite long, the list is searchable, so you can type part of the command you want to use.
Command completion extends regular completion
By default, the commands are shown in a separate section of the list. If you prefer Commands to be part of the regular completion list, you can adjust this in the Settings. Use Search Everywhere (Shift Shift) and look for “command completion” to go straight to the relevant settings and uncheck the option Show command completion as a separate group.
Command Completion Settings: Show command completion as a separate group
Fix errors and warnings with command completion
You can use this new feature to fix errors and warnings in your code. If you write code that doesn’t compile, IntelliJ IDEA will tell you. You can navigate to the error using F2 and press Alt+Enter to show context actions. However, Alt+Enter gives you only a few options; it is designed to give you the most relevant fixes to your problem. That means it might not always include the action you want to perform. On the other hand, command completion (..) offers you all actions that are relevant in your current context. IntelliJ IDEA will give you a preview of what each command will do.
Fix errors and warnings
Perform file- or class-level actions
It is now possible to unlock this type of completion in places where it wasn’t available before, like on a blank line. Typing a dot on a blank line now shows you file-level actions, like Reformat Code or Optimize Imports. For example, use Optimize Imports to remove an import statement that is no longer needed.
Perform file or class level actions
Refactoring and code transformation
Command completion can also help you when refactoring or transforming your code. When writing code, you can use it to keep moving forward. For example, to create classes, methods and fields.
Keep moving forward and create classes, methods and fields
You can use it to generate code for you, such as a toString() method.
You can transform your code as you go, for example to make use of modern Java language features. For example, you can refactor a class into a record, using only command completion.
Transform code
Use command completion for navigation
You can use it for navigation. For example, we can navigate to the String class declaration. You’ll notice that this file is read only! How will we use completion here? Don’t worry, you can change your settings to be able to use command completion in read-only files!
Open the Settings for Command Completion, by using Search Everywhere (Shift Shift) and searching for “command completion”. Select the option Enable command completion for read only files. Now, you can use command completion in read-only files, for example to navigate back to where you were.
Command Completion Settings: Enable command completion for read only files.
If you want to rename your class, you can use a shortcut to do so, but you need to know this shortcut (⇧F6 on macOS / Shift+F6 on Windows/Linux). Now, you can use command completion instead. Go to the end of the class or method name you want to rename and type ..rename.
Aliases for several commands
In some cases, you don’t even need to know the exact name of the command you’re looking for, as some commands have aliases. For example, you can also use ..change name instead of ..rename.
Aliases
This makes features even more discoverable; you don’t need to remember the exact name of the feature.
Imagine we declare a new instance of a class Person. To assign this new Person() to a variable, you can use the shortcut to Extract Variable (⌥⌘V on macOS / Ctrl+Alt+V on Windows/Linux). But this requires you to know this feature exists and the relevant shortcut.
Alternatively you could use postfix completion .var to create a variable. But that would again require you to know (or quickly be able to find) this specific postfix completion.
Instead, you can now use command completion to introduce a local variable. After the declaration of the new instance, use ..Introduce local variable.
Command completion complements existing features
If you want, you can still use postfix completion. For example, you type person.sout to print variable person to System.out: System.out.println(person);.
You can transform this code to modern Java and use features introduced in Java 25, like simple IO. After the line System.out.println(person); type .. and select ..Replace with IO.println().
You can use refactoring, like Extract Method (⌥⌘M on macOS / Ctrl+Alt+M on Windows/Linux), even if you don’t remember the shortcut. To do so, type .. and select ..Extract method after the method you want to extract.
Refactor: Extract method
What if you want to add JavaDoc to your code? You could use Alt+Enter to Add JavaDoc. But now you can also use command completion to generate JavaDoc, and convert it to Markdown.
Command completion is as easy as adding a dot, or two..
As you can see, using command completion is as easy as adding a dot, or two..
Conclusion
Command completion extends regular completion – which you already use. It lets you discover and use IntelliJ IDEA features without having to remember shortcuts. This keeps you in the flow of coding; you can think about what you want to do, instead of how to do it.
Type a . to find commands as part of regular completion, or .. to see all available commands relevant to your current context. You might discover powerful features you never knew were there!
IntelliJ IDEA is designed to help developers like us stay in the flow while we’re working. Like all IDEs, it has a lot of functionality available, but it’s designed to get out of your way to let you focus on the code.
Take a look at this overview of IntelliJ IDEA.
Introduction
Find Action: ⌘ ⇧ A (on macOS) / Ctrl+Shift+A (on Windows/Linux)
If you’re working on a real world project, you’re probably using external dependencies. You might need to analyze which dependencies your application uses. For example, you may want to find out how a particular version of a dependency ended up in your application. Let’s take a look at how IntelliJ IDEA can help you to analyze dependencies.
In this tutorial, we’re going to take a look at managing dependencies in IntelliJ IDEA. We’ll look at different ways to add dependencies to your project, and how to add, upgrade and remove dependencies using Package Search.
Add dependencies
There are several ways to add new dependencies to your project.
From the build file using copy-paste
You have probably copied a dependency from Maven Repository (or another website) and pasted into your build file.
For example, we can copy the Gradle format for this dependency and paste it into our build.gradle file.
Or, if we are using Maven, we can copy the Maven xml format into our pom.xml.
Did you know that if you copy-paste a Maven XML dependency into your build.gradle file, IntelliJ IDEA automatically turns it into the correct format for Gradle?
From the build file using code completion
We can also add dependencies to our build file using code completion. For example, let’s add a new dependency to our pom.xml.
We see that IntelliJ IDEA autocompletes the dependency xml, and we can search for the dependency we want, in this example AssertJ. If needed, the version number will also be added. Since this is a test dependency, we need to add the test scope, still using code completion.
Code completion works in Gradle too, as you can see below.
From the build file using code generation
We can also use code generation from the build file to add dependencies. In the build file, the pom.xml in a Maven project, invoke Package Search using ⌘N (on macOS) or Alt+Insert (on Windows & Linux) and in the menu that opens, select Add dependency. This will open the Dependencies tool window.
Note that if we are using Gradle, we can do the same in our build.gradle file.
From the Dependencies tool window
Alternatively, we can open the Dependencies tool window directly. There is no shortcut to open the Dependencies tool window, so we can either use Recent Files, ⌘E (on Mac) or Ctrl+E (on Windows/Linux), and type in “dependencies” to open the Dependencies tool window.
Alternatively, we can open it by clicking Quick Launch in the bottom-left and selecting Dependencies.
In the Dependencies tool window, we can search for a dependency. For example, let’s search for AssertJ.
Note that we can select a scope for this dependency. The names of the scopes are based on the build tool with which you are working. Since this is a test dependency, and we are using Gradle in this project, we can set the scope to testImplementation.
We can also select the version we want to use.
We can do the same in Maven.
Note that the names of scopes for Maven are different from Gradle. In Maven, we can set the scope for a test dependency to test.
When we click Add, we see that the dependency is added to the build file.
If the version number is shown in red, that means IntelliJ IDEA hasn’t downloaded this library before. Click Load Maven Changes so IntelliJ IDEA will update its dependencies based on the changes to the pom.xml or build.gradle file.
Go back to the Dependencies tool window and clear the search box by clicking the x on the right-hand side. You’ll see the project’s dependencies are updated with your new dependency.
Next, let’s look for jackson-databind. We see that there are several versions available. Since we have selected Only stable, only stable versions are shown in the list.
If we uncheck this option, we see that the list of versions also includes the release candidates.
For production code, we probably want to use stable versions, so let’s select the Only stable checkbox again. With this option enabled, IntelliJ IDEA will exclude any dependencies that have no stable versions, and hide them from the list. Now we can select the latest stable version and add this to our project. Let’s also Load Maven Changes again.
Finally, let’s also add a new dependency to the Kotlin module. Let’s switch to the Kotlin module and open the pom.xml for this module. Open the Dependencies Tool Window and search for Ktor.
Notice that some dependencies are marked as Multiplatform.
If we want to see only Kotlin multiplatform dependencies, we can select the Kotlin multiplatform checkbox, as shown below.
When we click Add to the right of the Ktor dependency, we see that Ktor is added to the list of dependencies and to the pom.xml for the Kotlin module.
Upgrade dependencies
We will also need to keep our dependencies up to date. To show you how IntelliJ IDEA can help, we are using this extremely outdated project as an example. In the pom.xml below, we see that several dependencies are marked with squiggly lines underneath them.
IntelliJ IDEA will show the suggestion to upgrade when we hover over the dependency, and we can click the suggestion to upgrade the dependencies.
Alternatively, we can use Context Actions ⌥⏎ (on macOS) or Alt+Enter (on Windows & Linux) to upgrade these dependencies.
We can also upgrade our dependencies using the Dependencies tool window. The Dependencies tool window will tell us if there’s a newer version of a dependency, as we can see here.
We can choose the version to upgrade to by clicking on the version number in the list. Note that we don’t have to use the latest version.
We can also automatically upgrade a dependency to the latest version by clicking Upgrade for that particular dependency.
Or, we can even upgrade all our dependencies at once, by clicking the Upgrade all link.
Remove dependencies
Finally, we can remove dependencies we no longer need. In the Dependencies tool window, let’s remove jackson-databind from the Java module. We select the dependency we want to remove (jackson-databind) and in the Dependency details pane on the right, click the More button (three dots) and select Remove.
We will see that the dependency is removed from the pom.xml and the dependency list. To remove a dependency from the whole project, select All Modules on the left.
Summary and Shortcuts
Now we know the different ways in which we can view our project’s dependencies in IntelliJ IDEA, and the different focus for each view.
IntelliJ IDEA Shortcuts Used
Here are the IntelliJ IDEA shortcuts that we used.
In this screencast, we’re going to take a look at managing dependencies in IntelliJ IDEA. We’ll look at different ways to add dependencies to your project, and how to add, update and remove dependencies using Package Search.
In this blogpost we’re going to take a look at different ways to view your external dependencies in IntelliJ IDEA.
Introduction
If you’re working on a real-world application, your project will probably use external libraries and frameworks. Occasionally, you might want to see which dependencies your project uses, for various reasons.
There are several ways to view dependencies in IntelliJ IDEA. Each view has a different focus.
Dependency management config file
You can find direct dependencies in the dependency management config file. Direct dependencies are the dependencies that your project depends on directly. They are declared in the dependency management config file.
One example is this pom.xml in a Maven project.
Maven pom.xml file
Another example is the build.gradle in a Gradle project.
Gradle build.gradle file
Note that the dependency management config file includes only declared dependencies and not their transitive dependencies (or the dependencies that these declared dependencies depend on).
Project tool window
In the Project tool window, ⌘1 (on Mac) or Alt+1 (on Windows/Linux), under External Libraries we can see all the JAR files needed by our application, including the transitive dependencies. However, we cannot tell the difference between direct dependencies and transitive dependencies. One declared dependency might bring in multiple JAR files.
Project tool window
Build tool window
To see direct dependencies and their transitive dependencies, we can look in the Build tool window. There is no shortcut to open the Build tool window. We can open it by clicking Quick Launch in the bottom-left and selecting Gradle, or Maven depending on what we’re using.
Open the Maven Build Tool Window in the Quick Launch menuOpen the Gradle Build Tool Window in the Quick Launch menu
Alternatively, we can open it by using Recent Files, ⌘E (on Mac) or Ctrl+E (on Windows/Linux), and typing “gradle” or “maven”, or the name of your build system.
Open the Gradle Build Tool Window using the Recent Files popup
Open the Maven Build Tool Window using the Recent Files popup
The Build tool window shows you each IntelliJ IDEA module separately, and each module’s “Dependencies” folder shows you all your dependencies in a hierarchical structure. We can expand our dependencies to see their transitive dependencies.
Finally, we can view and manage dependencies in the Dependencies tool window. The Dependencies tool window becomes available when the current project has at least one supported module. All types of dependencies are supported for Maven. For Gradle only a top level dependencies { } block is supported in the build script.
Since there is no shortcut to open the Dependencies tool window directly either, we can again use Recent Files, ⌘E (on Mac) or Ctrl+E (on Windows/Linux), and type in “dependencies” to open the Dependencies tool window.
Open the Dependencies Tool Window using the Recent Files popup
Alternatively, we can open it by clicking Quick Launch in the bottom-left and selecting Dependencies.
Open the Dependencies Tool Window in the Quick Launch menu
Here we can see our project’s direct dependencies. Select “All Modules” to see the dependencies for all modules, or select an indivual module to see the dependencies for that specific module. The Dependencies tool window shows direct dependencies, and not their transitive dependencies.
Dependencies Tool Window
We can see details about a selected dependency in the dependency details pane.
Dependency Details Pane
The dependency details pane displays the information about the selected dependency, such as:
Repository or repositories where it’s available, for example Maven Central
A description if it is available
GitHub information if the dependency sources are hosted on GitHub
The licence under which an open source library is available
A link to the project website, documentation and readme
List of usages in the current module.
Authors if available
Supported Kotlin or Multiplatform platforms if it is a Kotlin Multiplatform dependency
Summary and Shortcuts
Now we know the different ways in which we can view our project’s dependencies in IntelliJ IDEA, and the different focus for each view.
IntelliJ IDEA Shortcuts Used
Here are the IntelliJ IDEA shortcuts that we used.
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