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Console UI Module

The JLine Console UI module provides interactive prompt components for console applications, inspired by Inquirer.js. It offers a set of UI elements for creating user-friendly command-line interfaces.

ConsoleUI logo

Introduction​

ConsoleUI is a library for prompting the user for different types of input. It provides simple UI elements on ANSI console-based terminals. ConsoleUI was initially implemented using JLine2 by Andreas Wegmann and was later upgraded to use JLine3 and merged into the JLine project.

Features​

Console UI currently supports:

  • Text input with completion and GNU ReadLine compatible editing
  • Checkboxes for multiple selections
  • Lists for single item selection
  • Expandable choices (multiple key-based answers for a question with help)
  • Yes/No confirmation prompts

Watch a demo of ConsoleUI on YouTube

Quick Start Example​

Here's a simple example to get you started with ConsoleUI:

Loading snippet: ConsoleUIBasicExample...

Basic Usage​

The entry point to the builder classes is to create a new object of type ConsolePrompt. From the prompt object, use the getPromptBuilder() method to create the builder for all subsequent UI elements.

From this PromptBuilder you can access UI builders with the following methods:

  • createCheckboxPrompt(): Creates a checkbox prompt that lets the user choose any number of items from a list
  • createChoicePrompt(): Creates a choice prompt that lets the user choose one from a given number of possible answers
  • createConfirmPromp(): Creates a confirmation prompt that lets the user answer with 'yes' or 'no'
  • createInputPrompt(): Creates an input prompt for text entry with optional masking and completion
  • createListPrompt(): Creates a list prompt that lets the user choose one item from a list

Prompt Types​

Input Prompt​

The InputPrompt is a classic entry line like a shell. It offers completers and optional password masking.

Loading snippet: ConsoleUIInputExample...

Input prompt

The user can use readline compatible navigation (Emacs control codes) inside the input area, including CTRL-a to go to the beginning of input, CTRL-e to go to the end, and so on.

List Prompt​

The list prompt lets the user choose one item from a list.

Loading snippet: ConsoleUIListExample...

List prompt

The user can navigate with arrow keys or VI-like keys ('j' for down, 'k' for up) and select an item with Enter.

Checkbox Prompt​

The checkbox prompt lets the user choose any number of items from a list.

Loading snippet: ConsoleUICheckboxExample...

Checkbox prompt

The user can navigate with arrow keys and toggle selection with the space bar. Pressing Enter completes the input.

Expandable Choice Prompt​

The choice prompt lets the user choose one from a given number of possible answers, each assigned to a single keystroke.

Loading snippet: ConsoleUIChoiceExample...

Expandable choice prompt

By default, only the message and possible keys are displayed. If the user presses 'h' (for help), all possible answers with explanations are shown as a list.

Expandable choice prompt with help

Confirmation Prompt​

The confirmation prompt lets the user answer with 'yes' or 'no' to a question. This was shown in the Quick Start Example above.

Confirmation prompt

The user can press 'y' or 'n' to select between 'yes' and 'no', and Enter to confirm.

Advanced Features​

Page Size Control​

For long lists, you can control how many items are displayed at once:

// Set absolute number of items (default is 10)
.pageSize(15)

// Or set a percentage of terminal height (66 = 2/3 of terminal)
.relativePageSize(66)

Disabled Items​

You can disable items and display a message explaining why, as shown in the Checkbox example above with the pineapple topping:

.newItem("premium").text("Premium Feature").disabledText("Requires subscription").add()

Pre-checked Items​

For checkbox prompts, you can pre-check items as shown in the Checkbox example above:

// Method 1
.newItem("olives").text("Olives").check().add()

// Method 2
.newItem("special").text("Special").checked(true).add()

Maven Dependency​

To use the Console UI module in your Maven project, add the following dependency:

<dependency>
    <groupId>org.jline</groupId>
    <artifactId>jline-console-ui</artifactId>
    <version>${jline.version}</version>
</dependency>