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

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AvoidDecimalLiteralsInBigDecimalConstructor


AvoidDecimalLiteralsInBigDecimalConstructor
One might assume that "new BigDecimal(.1)" is exactly equal
     to .1, but it is actually equal
     to .1000000000000000055511151231257827021181583404541015625.
     This is so because .1 cannot be represented exactly as a double
     (or, for that matter, as a binary fraction of any finite length).
     Thus, the long value that is being passed in to the constructor
     is not exactly equal to .1, appearances notwithstanding.

     The (String) constructor, on the other hand, is perfectly predictable:
     'new BigDecimal(".1")' is exactly equal to .1, as one
     would expect.  Therefore, it is generally recommended that the (String)
     constructor be used in preference to this one.
  
		
		
		    
    			This rule is defined by the following XPath expression:
    			
    			
    
//AllocationExpression[ClassOrInterfaceType[@Image="BigDecimal"]
and
./Arguments/ArgumentList
/Expression/PrimaryExpression/PrimaryPrefix/Literal[(not
(ends-with
(@Image,'"'))) and contains(@Image,".")]]
 
    
  
		    
		    
	    
	    
        
        
        Example:
            
                    

import java.math.BigDecimal;
public class Test {

    public static void main(String[] args) {
      // this would trigger the rule
     BigDecimal bd=new BigDecimal(1.123);
      // this wouldn't trigger the rule
     BigDecimal bd=new BigDecimal("1.123");
      // this wouldn't trigger the rule
     BigDecimal bd=new BigDecimal(12);
    }
}