Custom PMD Rules
Subject:   Null check for an object
Date:   2006-03-21 22:15:56
From:   PravinD
please help me in writing the rule for the following scenario:

Before invoking any method of an object, a null check should be done.


String str1 = null;
String str2 = "ASP";

str2 = str1.toUpperCase(); // Which will throw NullPointerException.

So I have to ensure that this line is in the if check. Like,

String str1 = null;
String str2 = "ASP";

if(str1 != null)
str2 = str1.toUpperCase();

Any help would be appreciated. Which would be better a Java rule or XPATH rule?