commons-cli/xdocs/manual/validators.xml at cebd91b2dd09a826b2d22c604efaf71ebef123b0 · apache/commons-cli · GitHub

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<?xml version="1.0"?>
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<document>

  <properties>
    <author email="dev@commons.apache.org">commons-dev</author>
    <title>CLI2 - Validators</title>
  </properties>

  <body>
    <section name="Validators">
      <p>
        CLI2 provides a mechanism to validate argument values.  The <code>Validator</code>
        interface must be implemented to create an argument validator.  This interface has
        a single method <code>validate(java.util.List values) throws InvalidArgumentException</code>.
      </p>
      <p>
        CLI2 has some standard validators included.  They validate the following:
      </p>
      <ul>
        <li>Java class</li>
        <li>date</li>
        <li>enumeration</li>
        <li>file path</li>
        <li>number</li>
        <li>URL</li>
      </ul>

      <subsection name="ClassValidator">
        <p>
          The <code>ClassValidator</code> validates a value using three criteria:
        </p>
        <ol>
          <li>the value adheres to the Java Language Specification rules</li>
          <li>the class specified by the name is loadable</li>
          <li>the class specified by the name can be instantiated</li>
        </ol>
        <source>// 1.
ClassValidator validator = new ClassValidator();
// 2.
validator.setLoadable(true);
// 3.
validator.setLoadable(true);</source>
        <p>
        TODO: add section about values being replaced with class instances
        </p>
      </subsection>

      <subsection name="DateValidator">
        <p>
          The <code>DateValidator</code> validates values against a
          <code>java.text.DateFormat</code>.  There are three helper methods
          that create built-in validators.
        </p>
        <ol>
          <li><code>getDateInstance</code> returns a validator for the default
          date format for the default locale.
          </li>
          <li><code>getTimeInstance</code> returns a validator for the default
          time format for the default locale.
          </li>
          <li><code>getDateTimeInstance</code> returns a validator for the default
          date and time format for the default locale.
          </li>
        </ol>
        <p>
          A <code>DateValidator</code> can also be created by passing your
          a custom <code>DateFormat</code> into the constructor.
        </p>
        <source>DateFormat myFormat = DateFormat.getDateInstance( DateFormat.LONG, Locale.UK );
DateValidator myValidator = new DateValidator( myFormat );</source>
        <p>
          In addition to basic format checking you can also check if the date/time specified
          is before/after a specific date/time.  The lower bound is set using the
          <code>setMinimum( java.util.Date )</code>, and the upper bound is set using
          the <code>setMaximum( java.util.Date )</code>.
        </p>
        <p>
        TODO: add section about values being replaced with date instances
        </p>
      </subsection>

      <subsection name="EnumValidator">
        <p>
          The <code>EnumValidator</code> validates values against a list of
          allowed string values.  The values that are allowed are specified in
          a <code>java.util.Set</code> and passed in to the constructor.
        </p>
        <source>Set enumSet = new TreeSet();
enumSet.add("red");
enumSet.add("green");
enumSet.add("blue");

EnumValidator validator = new EnumValidator( enumSet );</source>
      </subsection>

      <subsection name="FileValidator">
        <p>
          The <code>FileValidator</code> validates that values represent
          existing files.  You can also specify a combination of the
          following additional criteria:
        </p>
        <ol>
          <li>value is a file</li>
          <li>value is a directory</li>
          <li>the file is writable</li>
          <li>the file is readable</li>
          <li>the file is hidden</li>
        </ol>
        <p>
          Each of the criteria listed here are specified using the appropriate
          setter.
        </p>
        <p>
          There are three helper methods to create validators:
        </p>
        <ol>
          <li><code>getExistingInstance</code> returns a validator that ensures
          a value represents an existing file.
          </li>
          <li><code>getExistingFileInstance</code> returns a validator that ensures
          a value represents an existing file that is not a directory.
          </li>
          <li><code>getExistingDirectoryInstance</code> returns a validator that ensures
          a value represents an existing file this is a directory.
          </li>
        </ol>
        <source>// validate that the value represents a file that exists
FileValidator validator = FileValidator.getExistingInstance();

// ensure it's not a hidden file
validator.setHidden( false );

// ensure it's a writable file
validator.setWritable( true );</source>

      </subsection>

      <subsection name="NumberValidator">
        <p>
          The <code>NumberValidator</code> validates that values adhere to
          certain rules like the following:
        </p>
        <ol>
          <li><code>getCurrencyInstance</code> returns a validator for the default
          currency format for the default locale.
          </li>
          <li><code>getPercentInstance</code> returns a validator for the default
          percent format for the default locale.
          </li>
          <li><code>getIntegerInstance</code> returns a validator for the default
          integer format for the default locale.
          </li>
          <li><code>getNumberInstance</code> returns a validator for the default
          number format for the default locale.
          </li>
        </ol>
        <p>
          A <code>NumberValidator</code> can also be created by passing your
          a custom <code>NumberFormat</code> into the constructor.
        </p>
        <source>NumberFormat myFormat = NumberFormat.getCurrencyInstance( Locale.UK );
NumberValidator myValidator = new NumberValidator( myFormat );</source>
        <p>
          In addition to basic format checking you can also check if the number specified
          is less than or greater than a specific number.  The lower bound is set using
          the <code>setMinimum( Number )</code>, and the upper bound is set using
          the <code>setMaximum( Number )</code>.
        </p>
      </subsection>

      <subsection name="UrlValidator">
        <p>
          A <code>UrlValidator</code> validates that values are URLs and if you
          choose it will also validate the protocol is of the type you have
          specified.
        </p>
        <source>UrlValidator validator = new UrlValidator();

// only accept https URLs
validator.setProtocol("https");</source>

      </subsection>

    </section>
  </body>
</document>