IntelliJ IDEA 2020.1 Help

Quick start with Go

This quick start guide will introduce you to the key concepts and help you with your first steps in IntelliJ IDEA.

Step 1. Open or create a Go project in IntelliJ IDEA

After you have installed the Go plugin and launched it for the first time, you need to create a project. Everything you do in IntelliJ IDEA is done within the context of a project. It serves as a basis for coding assistance, bulk refactoring, coding style consistency, and other features.

You have three options to start working on a project inside the IDE:

Open an existing project

  • To open a project that you store on your computer, click Open. In the file browser, navigate to a folder with project files and click Open.

    After you have opened your project, you need to specify the location of the Go SDK. You can specify a local path to the SDK or download it. To set the Go SDK, open settings Ctrl+Alt+S and navigate to Languages & Frameworks | Go | GOROOT. Click the Add SDK button and select between two options:

    • Local: use a local SDK copy. In the file browser, navigate to the SDK version that is on your hard drive.

    • Download: download the SDK. In the Location field, specify the path for the SDK. To use a file browser, click the Browse icon the Browse icon. Click OK.

    Welcome screen

Clone an existing project from a Version Control System

  1. Also, you can download sources from a VCS storage or repository. Click Get from Version Control and select between Git (GitHub) or Mercurial:

    • To сheck out files from GitHub, click GitHub, enter your credentials and click Log in. Enter a path to the sources and clone the repository to your computer.

    • To сheck out files from Mercurial, install and configure Mercurial and restart IntelliJ IDEA. Enter a path to the sources and clone the repository to your computer.

  2. After you have opened your project, you need to specify the location of the Go SDK. You can specify a local path to the SDK or download it. To set the Go SDK, open settings Ctrl+Alt+S and navigate to Languages & Frameworks | Go | GOROOT. Click the Add SDK button and select between two options:

    • Local: use a local SDK copy. In the file browser, navigate to the SDK version that is on your hard drive.

    • Download: download the SDK. In the Location field, specify the path for the SDK. To use a file browser, click the Browse icon the Browse icon. Click OK.

    For more information about version control systems, see Version control.

    Clone a repository

Create a new project

  1. To create a project, perform one of the following actions:

    • Select File | New | Project.

    • On the Welcome screen, click New Project.

  2. In the New Project dialog, select Go.

  3. In the GOROOT field, specify the Go SDK. You can select a local copy of SDK or download it.

    • To select a local copy of the Go SDK, click the Add SDK icon (the Add SDK icon) near the GOROOT field and select Local. In the file browser, navigate to the SDK version that is on your hard drive.

    • To download the Go SDK, click the Add SDK icon (the Add SDK icon) near the GOROOT field and select Download. From the Version list, select the SDK version. In the Target directory field, specify the path for the SDK. To use a file browser, click the Browse icon the Browse icon. Click OK.

  4. Click Next, specify a project name and click Finish.

    Download Go SDK

Create a Go file

  1. A new project has no Go files. To create a Go file, perform one of the following actions:

    • Right-click the parent folder of a project, and select New | Go File.

    • Click the parent folder of a project, pressAlt+Insert, and select Go File.

  2. In the New Go File dialog, type a name of the file and select whether you want to create an empty Go file (Empty file) or a Go file with the defined main function (Simple Application).

    Create a Go file

Step 2. Explore the user interface

When you launch IntelliJ IDEA for the very first time, you see the Welcome screen dialog. From the Welcome screen dialog, you can create and open projects, check out a project from a version control system, view documentation, and configure the IDE.

When a project is opened, you see the main window divided into several logical areas.

Project view, Editor, and Tool Windows
  1. The Project tool window, which is on the left side, displays your project files. Tool windows are windows that provide access to project management, search, running and debugging, integration with version control systems, and other tasks. To see a list of all tool windows, navigate to View | Tool Windows.

  2. The Editor pane is on the right side, where you write your code. It has tabs for easy navigation between open files.

  3. The navigation bar is above the editor additionally allows you to quickly run and debug your application as well as do basic VCS actions.

  4. The Gutter is the vertical stripe next to the editor. It shows you the breakpoints and provides a convenient way to navigate to a definition or a declaration. Also, you can use the Run Application icon (the Run Application icon) to run or to debug your application.

  5. The Scrollbar, on the right side of the editor. IntelliJ IDEA monitors the quality of your code and shows the results of code inspections: errors, warnings, typos, and other issues. The indicator at the top of the gutter shows the overall status of code inspections for the entire file.

  6. The status bar indicates the status of your project and the entire IDE and shows you information about a file encoding, line separators, inspection profiles, and other warnings and information messages.

In the lower left part of the IDE, in the Status bar, you can see Show tool window bars or Hide tool window                 bars buttons. These buttons toggle the display of the tool window popup. If you hover your mouse pointer over this button, the list of the currently available tool windows shows up.

Step 3. Write your code

As you work in the editor, IntelliJ IDEA analyzes your code, searches for ways to optimize it, and detects potential and actual problems. The following list includes basic features and tools that might be useful for your code writing and increase your productivity:

Refactorings

Refactoring is a process of improving your source code without creating a new functionality. Refactoring helps you keep your code solid, dry, and easy to maintain.

IntelliJ IDEA suggests you the following refactoring options:

  • Change signature changes the method or function name; adds, removes, and reorders parameters; assigns default values to new non-variadic parameters.

  • Extract refactorings extracts code fragments that can be grouped. You can extract a constant, a variable, a method, and an interface.

  • Inline refactoring moves an extracted code fragment to the calling code. An opposite to the Extract refactoring.

  • Copy refactoring copies a file, a directory, or a package to a different directory or a package.

  • Move refactoring moves source code sections to another package or a file. For example, you can use the Move refactoring to move methods to another package.

Code completion

IntelliJ IDEA has two types of code completion:

  • Basic code completion Ctrl+Space helps you complete names of types, interfaces, methods, and keywords within the visibility scope. When you invoke code completion, IntelliJ IDEA analyzes the context and suggests the choices that are reachable from the current caret position. By default, IntelliJ IDEA displays the code completion popup automatically as you type.

  • Smart code completion Ctrl+Shift+Space filters the suggestions list and shows only the types applicable to the current context.

    The following animation shows the difference between basic and smart completion. Notice the number of variants that are suggested for different completion types

Generating code

IntelliJ IDEA provides multiple ways to generate common code constructs and recurring elements, which helps you increase productivity. These can be either predefined or custom templates that are applied differently based on the context, various wrappers, and automatic pairing of characters.

Additionally, IntelliJ IDEA provides code completion and Emmet support.

From the main menu, select Code | Generate Alt+Insert to open the popup menu with available constructs that you can generate.

  • You can generate getters, setters, constructors, missing methods, and test files.

Live templates

Use live templates to insert common constructs into your code, such as loops, conditions, various declarations, or print statements.

To expand a code snippet, type the corresponding template abbreviation and press Tab. Keep pressing Tab to jump from one variable in the template to the next one. Press Shift+Tab to move to the previous variable.

  • To see the list of live templates, open settings Ctrl+Alt+S and navigate to Editor | Live templates.

    Consider the following example of the Hello World program that is coded with Live Templates.

Inspections

In IntelliJ IDEA, there is a set of code inspections that detect and correct anomalous code in your project before you compile it. The IDE can find and highlight various problems, locate dead code, find probable bugs, spelling problems, and improve the overall code structure.

Inspections can scan your code in all project files, or only in specific scopes (for example, only in production code, or in modified files).

Every inspection has a severity level — the extent to which a problem can affect your code. Severities are highlighted differently in the editor so that you can quickly distinguish between critical problems and less important things. IntelliJ IDEA comes with a set of predefined severity levels and enables you to create your own.

  • To see the list of inspections, open settings Ctrl+Alt+S and navigate to Editor | Inspections. Disable some of them, or enable others, plus adjust the severity of each inspection. You decide whether it should be considered an error or just a warning.

    For example, the Unreachable code inspection detects parts of code that cannot be executed.

    The unreachable code inspection

Intention actions

As you work in the editor, IntelliJ IDEA analyzes your code, searches for ways to optimize it, and detects potential and actual problems.

As soon as the IDE finds a way to alter your code, it displays a yellow bulb icon yellow bulb icon in the editor next to the current line. By clicking this icon, you can view intention actions available for this unit of code. Intention actions cover a wide range of situations from warnings to optimization suggestions. You can view the full list of intentions and customize them in the Settings/Preferences dialog Ctrl+Alt+S.

To see the list of intention actions, open settings Ctrl+Alt+S and navigate to Editor | Intentions.

  1. To apply an intention action, click the bulb icon (or press Alt+Enter) to open the list of suggestions.

  2. Select an action from the list and press Enter.

    For example, you can use an intention action to inject another language in your code:

Step 4. Run and debug your code

You can run and debug your code in IntelliJ IDEA from a keyboard, from the context menu, from the gutter menu, or by using the Run/Debug configuration.

Run your code

  • To run your application Shift+F10, click the Run Application icon Run and select Run <application_name>.

    Run your code from the gutter

Debug your code

Debugging starts with placing breakpoints at which program execution will be suspended so that you can explore program data. Just click the line in the gutter where you want to place a breakpoint.

  • To debug your application Shift+F9, click the Run Application icon Run and select Debug <application_name>. Then go through the program execution step by step (see the available options in the Run menu or the Debug tool window).

    Refer to the section Debugging for details.

    Debug your code
Last modified: 25 May 2020