Equals operator for zeros (BigDecimal / Double) in Java

Question

A few interesting observations w.r.t equals operator on 0 and 0.0

1. new Double(0.0).equals(0) returns false, while new Double(0.0).equals(0

Answer 1

new Double(0.0).equals(0); //false

as the argument you passed is integer. and the equels() in Double class checks whether the argument is od instance Double or not using instance of operator.

The Double's equals() method.

if (!(argument instanceof Double))
  return false;

The argument you passed is integer, which is not instance of Double, so it returns false.