resources.report.rules.pmd.UseArraysAsList.html Maven / Gradle / Ivy

Go to download


UseArraysAsList


UseArraysAsList
The class java.util.Arrays has a "asList" method that
   should be use when you want to create a new List from
   an array of objects. It is faster than executing a loop to
   cpy all the elements of the array one by one
     
		
		
		    
    			This rule is defined by the following XPath expression:
    			
    			
       
//Statement[
    (ForStatement) and (count(.//IfStatement)=0)
   ]
   //StatementExpression[
    PrimaryExpression/PrimaryPrefix/Name[
	 substring-before(@Image,'.add') = ancestor::MethodDeclaration//LocalVariableDeclaration[
      ./Type//ClassOrInterfaceType[
       @Image = 'Collection' or 
       @Image = 'List' or @Image='ArrayList'
      ]
     ]
     /VariableDeclarator/VariableDeclaratorId[
      count(..//AllocationExpression/ClassOrInterfaceType[
       @Image="ArrayList"
      ]
      )=1
     ]/@Image
    ]
   and
   PrimaryExpression/PrimarySuffix/Arguments/ArgumentList/Expression/PrimaryExpression/PrimaryPrefix/Name
   [@Image = ancestor::MethodDeclaration//LocalVariableDeclaration
   [@Array="true"]/VariableDeclarator/VariableDeclaratorId/@Image]
   /../..[count(.//PrimarySuffix)
   =1]/PrimarySuffix/Expression/PrimaryExpression/PrimaryPrefix
   /Name
   ]
   
       
  
		    
		    
	    
	    
        
        
        Example:
            
                    
   
   public class Test {
    public void foo(Integer[] ints) {
    // could just use Arrays.asList(ints)
     List l= new ArrayList(10);
     for (int i=0; i< 100; i++) {
      l.add(ints[i]);
     }
     for (int i=0; i< 100; i++) {
      l.add(a[i].toString()); // won't trigger the rule
     }
    }
   }