TIOBE - Java Coding Standard

Rule: StringandStringBuffer10

Synopsis:	String.trim().length()==0 is an inefficient way to validate an empty String
Language:	Java
Severity Level:	4
Category:	StringandStringBuffer

Description:

String.trim().length() is an inefficient way to check if a String is really empty, as it creates a new String object just to check its size. Consider creating a static function that loops through a string, checking Character.isWhitespace() on each character and returning false if a non-whitespace character is found.

public class Foo {
    void bar(String string) {
        if (string != null && string.trim().size() > 0) { 
		    doSomething();
        } 
    }
}