Using toLowerCase() or toUpperCase() to make case insensitive comparisons is inefficient because it requires the creation of temporary, intermediate String objects.

The following code:

boolean result1 = foo.toUpperCase().equals(bar);             // Non-Compliant
boolean result2 = foo.equals(bar.toUpperCase());             // Non-Compliant
boolean result3 = foo.toLowerCase().equals(bar.LowerCase()); // Non-Compliant

should be refactored into:

boolean result = foo.equalsIgnoreCase(bar);                  // Compliant