Airline

Annotation-driven Java framework for building powerful Git style CLIs in Java

Stable Version: 3.2.0 Development Version: 3.2.1-SNAPSHOT
All content on this site is open source under the Apache License 2.0

Pattern Annotation

@Pattern

The @Pattern annotation may be applied to fields annotated with @Option and @Arguments to limit the values of the option to those matching a given regular expression e.g.

@Option(name = "--tel")
@Pattern(pattern = "(\\+1-)?\\d{3}-\\d{3}-\\d{4}", 
         description = "Must provide a telephone number in standard US format e.g. +1-800-123-4567")
public String tel;

Here we require that the --tel option be a telephone number in the standard US format.

The use of the optional description field of the annotation allows us to supply a user friendly error message. If this is not specified users will receive a potentially cryptic error message containing the regular expression they failed to match.

Regular Expression Flags

You can use the flags field of the annotation to specify the flags that apply to the regular expression. Airline uses the standard JVM java.util.regex.Pattern and so this field takes an integer which is interpreted as a bitmask of the various JVM constants e.g.

@Option(name = "--other")
@Pattern(pattern = "foo|bar|foobar", flags = java.util.regex.Pattern.CASE_INSENSITIVE)
public String other;

Requires that the option meet the regular expression case insensitively i.e. FOO would be considered a valid value under this regular expression

To restrict values to specific sets of values it is likely more efficient to use the @AllowedRawValues or @AllowedValues annotations.

To place simple string related restrictions some combination of @NotBlank, @NotEmpty, @MaxLength and @MinLength may also be useful.

For simple prefix/suffix constraints you can use the @StartsWith and @EndsWith annotations.

Improving this Documentation

This documentation is itself open source and lives in GitHub under the docs/ directory.

I am not a professional technical writer and as the developer of this software I can often make assumptions of knowledge that you as a user reading this may not have. Improvements to the documentation are always welcome, if you have suggestions for the documentation please submit pull requests to the main branch.