Package net.sourceforge.pmd.lang.java.rule.performance

Class InefficientEmptyStringCheckRule

  • All Implemented Interfaces:
    AstVisitor<Object,​Object>, JavaParserVisitor, JavaVisitor<Object,​Object>, PropertySource, Rule
    public class InefficientEmptyStringCheckRule
extends AbstractJavaRulechainRule
    This rule finds code which inefficiently determines empty strings. 

     str.trim().length()==0
    or 
     str.trim().isEmpty()
    (for the same reason) is quite inefficient as trim() causes a new String to be created. A Smarter code to check for an empty string would be: 
     private boolean checkTrimEmpty(String str) {
     for(int i = 0; i < str.length(); i++) {
         if(!Character.isWhitespace(str.charAt(i))) {
             return false;
         }
     }
     return true;
 }
    or you can refer to Apache's StringUtils#isBlank (in commons-lang), Spring's StringUtils#hasText (in the Spring framework) or Google's CharMatcher#whitespace (in Guava) for existing implementations (some might include the check for != null).

    Author:
    acaplan

    • Constructor Detail

      • InefficientEmptyStringCheckRule

        public InefficientEmptyStringCheckRule()