Double.valueOf(s) vs. Double.parseDouble

Question

Casting an Object to a double and noticed both these methods. I see that parseDouble has been in since 1.2. Why add this method if it essentially does the same functionality as valueOf(s)?

Answer 1

parseDouble() returns a primitive double value. valueOf() returns an instance of the wrapper class Double. Before Java 5 introduced autoboxing, that was a very significant difference (and many would argue it still is).

Answer 2

Because it is not the same. valueOf() creates a Double object which is often not needed. parseDouble() does not. With autoboxing it's valueOf(String) which is no longer needed, but is therefore backward compatibility.

Answer 3

If you just need the value (primitive) use parseDouble(String s) the cost is less. valueOf(String s) returns a Double class which wraps the primitive double value.