maven-plugins/pmd/rulesets/imports.xml

<?xml version="1.0"?>

<ruleset name="Import Rules">
  <description>
These rules deal with different problems that can occur with a class' import statements.
  </description>

  <rule name="DuplicateImports"
        message="Avoid duplicate imports such as ''{0}''"
        class="net.sourceforge.pmd.rules.DuplicateImportsRule">
    <description>
    Avoid duplicate import statements.
    </description>

    <example>
<![CDATA[
// this is bad
import java.io.File;
import java.io.File;
public class Foo {}

// --- in another source code file...

// this is bad
import java.io.*;
import java.io.File;

public class Foo {}
]]>
    </example>
    </rule>

  <rule name="DontImportJavaLang"
        message="Avoid importing anything from the package 'java.lang'"
        class="net.sourceforge.pmd.rules.DontImportJavaLangRule">
    <description>
    Avoid importing anything from the package 'java.lang'.  These classes are automatically imported (JLS 7.5.3).
    </description>

    <example>
<![CDATA[
// this is bad
import java.lang.String;
public class Foo {}

// --- in another source code file...

// this is bad
import java.lang.*;

public class Foo {}
]]>
    </example>
    </rule>

  <rule name="UnusedImports"
        message="Avoid unused imports such as ''{0}''"
        class="net.sourceforge.pmd.rules.UnusedImportsRule">
    <description>
    Avoid unused import statements.
    </description>

    <example>
<![CDATA[
// this is bad
import java.io.File;
public class Foo {}
]]>
    </example>
    </rule>

</ruleset>