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

Class InefficientEmptyStringCheckRule

java.lang.Object
net.sourceforge.pmd.properties.AbstractPropertySource
net.sourceforge.pmd.lang.rule.AbstractRule
net.sourceforge.pmd.lang.java.rule.AbstractJavaRule
net.sourceforge.pmd.lang.java.rule.AbstractJavaRulechainRule
net.sourceforge.pmd.lang.java.rule.performance.InefficientEmptyStringCheckRule
All Implemented Interfaces:
AstVisitor, JavaVisitor, Rule, PropertySource
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 Details

    • InefficientEmptyStringCheckRule

      public InefficientEmptyStringCheckRule()

  • Method Details