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Easy to use command-line parser, which enables you to define cmdline flags directly the class they are used in.

There is a newer version: 0.3.0-beta2

package com.github.yin.flags;

/**
 * Provides Flag value access and validation to client classes. Flag value is injected into static
 * fields of type {@link Flag} and accessed using {@link #get()}.
 *
 * {@link #parse(String)} is never used by client classes, but should be implemented if a custom
 * return type is desired from {@link #get()}.
 *
 * @author yin
 */
public interface Flag {
    /**
     * Validates parsed flag values. May be used to enforce compile-time constraints safely and
     * also run-time if care is taken to avoid lockup in a mutually recursive chain of {@link #get()}'s.
     */
    @FunctionalInterface
    interface Validator {
        void validate(T value);
    }

    /**
     * Attaches a {@link Validator} function to this flag instance.
     */
    Flag validator(Validator validator);

    /**
     * Attempts parsing a {@link String} representation of a value and is responsible for calling
     * the validator function afterwards.
     */
    void parse(String value);

    /**
     * Returns value stored in the flag, possibly a default value.
     */
    T get();
}