Double subtraction precision issue

Question

My coworker did this experiment:

public class DoubleDemo {

      public static void main(String[] args) {
           double a = 1.435;
           double b =         


        

Answer 1

 //just try to make a quick example to make b to have the same precision as a has, by using BigDecimal

 private double getDesiredPrecision(Double a, Double b){
     String[] splitter = a.toString().split("\\.");
     splitter[0].length();   // Before Decimal Count
     int numDecimals = splitter[1].length(); //After Decimal Count

     BigDecimal bBigDecimal = new BigDecimal(b);
     bBigDecimal = bBigDecimal.setScale(numDecimals,BigDecimal.ROUND_HALF_EVEN);

     return bBigDecimal.doubleValue();  
 }