JBehave is an open source BDD framework originally written by Dan North, the inventor of BDD. It is strongly integrated into the JVM world, and widely used by Java development teams wanting to implement BDD practices in their projects.

In JBehave, you write automate your acceptance criteria by writing test stories and scenarios using the familiar BDD "given-when-then" notation, as shown in the following example:

Scenario: Searching by keyword and category

Given Sally wants to buy some antique stamps for her son
When she looks for ads in the 'Antiques' category containing 'stamps'
Then she should obtain a list of ads related to 'stamps' from the 'Antiques' category

Scenarios like this go in .story files: a story file is designed to contain all the scenarios (acceptence criteria) of a given user story. A story file can also have a narrative section at the top, which gives some background and context about the story being tested:

In order to find the items I am interested in faster
As a buyer
I want to be able to list all the ads with a particular keyword in the description or title.

Scenario: Searching by keyword and category

Given Sally wants to buy some antique stamps for her son
When she looks for ads in the 'Antiques' category containing 'stamps'
Then she should obtain a list of ads related to 'stamps' from the 'Antiques' category

Scenario: Searching by keyword and location

Given Sally wants to buy a puppy for her son
When she looks for ads in the Pets & Animals category containing puppy in New South Wales
Then she should obtain a list of Pets & Animals ads containing the word puppy
  from advertisers in New South Wales

You usually implement a JBehave story using classes and methods written in Java, Groovy or Scala. You implement the story steps using annotated methods to represent the steps in the text scenarios, as shown in the following example:

public class SearchSteps {
    @Given("Sally wants to buy a $gift for her son")
    public void sally_wants_to_buy_a_gift(String gift) {
        // test code
    }

    @When("When she looks for ads in the $category category containing $keyword in $region")
    public void looking_for_an_ad(String category, String keyword, String region){
        // more test code
    }
}