Need help to write - null check for objects

[512Renee]

Dear All,

I need a null check rule for an object, before we retrieve values from an object.

eg:
Class Foo{

int A;
String B;
.
.
}

if (foo.getA() > 5){
}

If any operation is done on the object without a null check, it has to be highlighted and logged..
Thanks in anticipation!

[Andreas Dangel]

I would recommend to check out the rules MisplacedNullCheck and BrokenNullCheck.

Example with XPath (beware - it might have lots of false positives/negatives):

<rule  name="NullCheck"
  message="Null Check is required."
  class="net.sourceforge.pmd.lang.rule.XPathRule"
  language="java">
  <description>

  </description>
  <properties>
    <property name="xpath">
    <value>
<![CDATA[

//IfStatement/Expression
[.//PrimarySuffix[../PrimaryPrefix/Name[contains(@Image, '.')]]]
[
count(.//NullLiteral[ancestor::EqualityExpression[@Image='!=']
  [starts-with(following-sibling::*/PrimaryExpression/PrimaryPrefix/Name/@Image,./PrimaryExpression/PrimaryPrefix/Name/@Image)]
]) = 0]

]]>
    </value>
    </property>
  </properties>
  <priority>3</priority>
  <example>
<![CDATA[
public class Foo{
  int A;

  public int getA() {
    return A;
  }

  public static void check() {
    Foo foo = new Foo();
    Foo bar = new Foo();

    // missing null check
    if (foo.getA() > 5){ }
    // missing null check
    if (bar != null && foo.getA() > 5) {}
    // correct null check
    if (foo != null && foo.getA() > 5) { }
  }
}
]]>
  </example>
</rule>

[512Renee]

Thanks a ton!! :)
I will take it further by testing rigorously, and keep you posted..

Thank you very much again.

[512Renee]

Hi Andreas,

it is not working when I try to add it as a rule in eclipse-pmd plugin.

Please give me some pointers to look into..

Thanks.