TIOBE - Java Coding Standard

Rule: Basic26

This rule is Obsolete
Synopsis:	Invoke equals() on the object you've already ensured is not null
Language:	Java
Severity Level:	2
Category:	Basic

Description:

After checking an object reference for null, you should invoke equals() on that object rather than passing it to another object's equals() method.


public class Test {

  public void method(String a, String b) {

    if (a != null && method1().equals(a)) { // will trigger the rule, because "a" is certainly not null
      //whatever
    }

    if (method1().equals(a)) { // won't trigger the rule, nothing is known about "a" or "method1"
      //whatever
    }

    if ("LITERAL".equals(a)) { // won't trigger the rule, because "LITERAL" is non-null by definition
      //whatever
    }

    if (a.equals("LITERAL")) { // will trigger the rule, because nothing is known about "a"
      //whatever
    }
  }
}