maven-plugins/pmd/rulesets/design.xml

<?xml version="1.0"?>

<ruleset name="Design Rules">
  <description>
The Design Ruleset contains a collection of rules that find questionable designs.
  </description>


  <rule name="UseSingletonRule"
        message="All methods are static.  Consider using Singleton instead."
        class="net.sourceforge.pmd.rules.design.UseSingletonRule">
    <description>
    If you have a class that has nothing but static methods, consider making it a Singleton
    </description>

    <example>
<![CDATA[
public class MaybeASingleton {
    public static void foo() {
     // etc
    }
    public static void bar() {
     // etc
    }
}
]]>
    </example>
  </rule>


  <rule name="LooseCouplingRule"
        message="Avoid using implementation types like ''{0}''; use the interface instead"
        class="net.sourceforge.pmd.rules.design.LooseCouplingRule">
    <description>
    Avoid using implementation types (i.e., HashSet); use the interface (i.e, Set) instead
    </description>

    <example>
<![CDATA[
import java.util.*;
public class Bar {

 // should be "private List list"
 private ArrayList list = new ArrayList();

 // should be "public Set getFoo()"
 public HashSet getFoo() {
  return new HashSet();
 }
}

]]>
    </example>
  </rule>


  <rule name="SimplifyBooleanReturnsRule"
        message="Avoid unnecessary if..then..else statements when returning a boolean"
        class="net.sourceforge.pmd.rules.SimplifyBooleanReturnsRule">
    <description>
Avoid unnecessary if..then..else statements when returning a boolean
    </description>
    <example>
<![CDATA[
public class Foo {
  private int bar =2;
  public boolean isBarEqualsTo(int x) {
    // this bit of code
    if (bar == x) {
     return true;
    } else {
     return false;
    }
    // can be replaced with a simple
    // return bar == x;
  }
}
]]>
    </example>
  </rule>


  <rule name="SwitchStmtsShouldHaveDefault"
        message="Switch statements should have a default label"
        class="net.sourceforge.pmd.rules.SwitchStmtsShouldHaveDefaultRule">
    <description>
    Switch statements should have a default label.
    </description>

    <example>
<![CDATA[
public class Foo {
 public void bar() {
  int x = 2;
  switch (x) {
   case 2: int j = 8;
  }
 }
}
]]>
    </example>
    </rule>

   <rule name="OnlyOneReturn"
        message="A method should have only one exit point, and that should be the last statement in the method"
        class="net.sourceforge.pmd.rules.design.OnlyOneReturnRule">
    <description>
    A method should have only one exit point, and that should be the last statement in the method.
    </description>

    <example>
<![CDATA[
public class OneReturnOnly1 {
 public void foo(int x) {
  if (x > 0) {
   return "hey";   // oops, multiple exit points!
  }
  return "hi";
 }
}
]]>
    </example>
    </rule>


  <rule name="AvoidDeeplyNestedIfStmts"
        message="Deeply nested if..then statements are hard to read"
        class="net.sourceforge.pmd.rules.AvoidDeeplyNestedIfStmtsRule">
    <description>
    Deeply nested if..then statements are hard to read.
    </description>
   <properties>
    <property name="problemDepth" value="3"/>
   </properties>
    <example>
<![CDATA[
public class Foo {
 public void bar() {
  int x=2;
  int y=3;
  int z=4;
  if (x>y) {
   if (y>z) {
    if (z==x) {
     // this is officially out of control now
    }
   }
  }
 }
}
]]>
    </example>
    </rule>


    <rule name="AvoidReassigningParametersRule"
        message="Avoid reassigning parameters such as ''{0}''"
        class="net.sourceforge.pmd.rules.AvoidReassigningParametersRule">
    <description>
Reassigning values to parameters is a questionable practice.  Use a temporary local variable instead.
    </description>
    <example>
<![CDATA[
public class Foo {
 private void foo(String bar) {
  bar = "something else";
 }
}
]]>
    </example>
  </rule>

  </ruleset>