https://github.com/valid4j/valid4j

Simple assertion and validation library for Java
https://github.com/valid4j/valid4j

Last synced: about 2 months ago
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Simple assertion and validation library for Java

• Host: GitHub
• URL: https://github.com/valid4j/valid4j
• Owner: valid4j
• License: apache-2.0
• Created: 2014-02-18T22:53:40.000Z (about 11 years ago)
• Default Branch: master
• Last Pushed: 2022-01-16T14:01:53.000Z (about 3 years ago)
• Last Synced: 2024-04-17T22:48:59.410Z (12 months ago)
• Language: Java
• Homepage: http://www.valid4j.org/
• Size: 1.02 MB
• Stars: 48
• Watchers: 6
• Forks: 7
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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• awesome-java - Valid4j

README

        
valid4j

=======

[![Build Status](https://travis-ci.org/valid4j/valid4j.png)](https://travis-ci.org/valid4j/valid4j)

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[![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.valid4j/valid4j/badge.png)](https://maven-badges.herokuapp.com/maven-central/org.valid4j/valid4j)

A simple assertion and validation library for Java which makes it possible to use your

favorite [hamcrest-matchers](http://hamcrest.org/JavaHamcrest/) to 

express pre- and post-conditions in your code. Use the global default 

policy to signal logical violations in your code or optionally specify 

your own handling.

Full documentation is available at [www.valid4j.org](http://www.valid4j.org).

This library is available at [Maven Central Repository](http://search.maven.org/).

Add this dependency to your `pom.xml`

    

      org.valid4j

      valid4j

      0.5.0

    

### Design-by-contract (assertions)

Statically import the library entry point:

    import static org.valid4j.Assertive.*;

Use assertive preconditions to check for programming errors in calling clients:

    // Express your preconditions using plain boolean expressions, with a helpful error message (optional)

    require(v > 0.0, "The value (%f) must be positive", v);

    

    // Or use hamcrest-matchers

    require(v, containsString("great!"));

    

Use assertive postconditions to check for programming errors in your supplied code:

    ensure(result != null);

    ensure(result, greaterThan(3.0));

    

Make use of the convenient pass-through of valid objects:

    // Initialize members with valid arguments

    this.member = require(argument, notNullValue());

    // Return valid results

    return ensure(result, notNullValue());

Contract violations will contain a descriptive error message:

    // E.g this contract

    require("This message is bad", containsString("good"));

    

    // Will yield this error

    org.valid4j.exceptions.RequireViolation: expected: a string containing "good"

     but: was "This message is bad"

### Validation (e.g. input validation)

Statically import the library entry point:

    import static org.valid4j.Validation.*;

Use expressive hamcrest-matchers to validate input

    validate(argument, isValid(), otherwiseThrowing(InvalidException.class));

Make use of the convenient pass-through of valid objects:

    // Initialize members with valid arguments

    this.member = validate(arg, isValid(), otherwiseThrowing(InvalidException.class));

Failed validations will contain a descriptive message:

    // E.g this validation

    validate("This message is bad", containsString("good"), IllegalArgumentException.class);

    

    // Will yield this exception with message

    // (NOTE: Exception class must accept one String argument in constructor for this feature to be supported)

    java.lang.IllegalArgumentException: expected: a string containing "good"

     but: was "This message is bad"