Terminal Providers
JLine supports multiple terminal providers, each with its own characteristics and capabilities. This allows JLine to work across different platforms and environments.
JLine 4.x has removed the JNA and Jansi providers. These providers are no longer available and have been replaced by more modern alternatives.
The recommended providers for JLine 4.x are JNI (for maximum compatibility) and FFM (for best performance on Java 22+).
Provider Selection
JLine can automatically select the best terminal provider for your environment, or you can explicitly specify which provider to use:
Loading snippet: ProviderSelectionExample...
JNA Provider (Removed in JLine 4.x)
The JNA (Java Native Access) provider has been removed in JLine 4.x. Use the JNI or FFM providers instead for native terminal functionality.
Jansi Provider (Removed in JLine 4.x)
The Jansi provider has been removed in JLine 4.x. Use the JNI or FFM providers instead for ANSI support and terminal functionality.
FFM Provider
The FFM (Foreign Function & Memory) provider uses Java's FFM API (available in Java 22+) to access native terminal functionality:
Loading snippet: FfmTerminalExample...
The FFM provider is compiled with Java 22 bytecode and requires:
- Java 22 or later to run
- Native access permissions at runtime:
--enable-native-access=org.jline.terminal.ffm(module path) or--enable-native-access=ALL-UNNAMED(classpath)
If you're using Java 11-21, the FFM provider will be automatically skipped during provider selection, or you can use the jdk11 classifier to exclude it entirely from your classpath.
See JPMS documentation for more details on native access configuration.
Using the JDK11 Classifier
If you're building your project with Java 11-21 and want to avoid Java 22 class files in your dependencies, use the jdk11 classifier for the jline bundle:
Maven:
<dependency>
<groupId>org.jline</groupId>
<artifactId>jline</artifactId>
<version>4.0.0</version>
<classifier>jdk11</classifier>
</dependency>
Gradle:
implementation 'org.jline:jline:4.0.0:jdk11'
The jdk11 classifier artifact:
- Excludes the
org.jline.terminal.impl.ffm.*classes (compiled with Java 22) - Contains all other JLine functionality
- Compatible with Java 11-21
- Automatically uses JNI or Exec providers for native terminal access
This is particularly useful when:
- Your build tools warn about class file version mismatches
- You're targeting Java 21 or earlier
- You need to avoid dependencies with newer bytecode versions
Note: For JLine 3.x, use the jdk8 classifier which is compatible with Java 8-21.
JNI Provider
The JNI (Java Native Interface) provider uses JNI to access native terminal functionality:
Loading snippet: JniTerminalExample...
Exec Provider
The Exec provider uses external commands to access terminal functionality:
Loading snippet: ExecTerminalExample...
Dumb Terminal
The Dumb terminal is a fallback option that provides basic terminal functionality without advanced features:
Loading snippet: DumbTerminalExample...
Best Practices
When working with terminal providers in JLine, consider these best practices:
-
Auto-Selection: Let JLine automatically select the best provider for your environment when possible.
-
Fallback Strategy: Implement a fallback strategy if a specific provider is not available.
-
Feature Detection: Check for terminal capabilities before using advanced features.
-
Cross-Platform Testing: Test your application on different platforms to ensure it works with different providers.
-
Error Handling: Handle terminal-related errors gracefully.
-
Terminal Cleanup: Always close the terminal when your application exits.
-
Signal Handling: Handle terminal signals (like SIGINT) appropriately.
-
Terminal Size: Be aware of terminal size and adapt your UI accordingly.
-
Color Support: Check for color support before using colors.
-
Documentation: Document which terminal providers your application supports.