Can new Double(String) ever return a null?

Question

Given this code

final Double price = new Double(someString);
if(price != null <...>) {

Am I correct in assuming that price can NEVER be null here?

If you separate the declaration from the assignment and have a try catch around the assignment then price might be null if `someString` is not a number (depending on what you do with the exception) — blank, May 15 '13 at 07:47

score 6 · Answer 1 · answered May 15 '13 at 07:43

6

It can thrown NumberFormatException but it can never be null, because you are using the new keyword.

answered May 15 '13 at 07:43

Habib

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I liked your answer and upvoted it, but gave the edge to the one that cites the actual spec. – Anders Johansen May 15 '13 at 08:01

score 4 · Accepted Answer · answered May 15 '13 at 07:44

Read the specifications: section 15.9.4 of the JLS:

The value of a class instance creation expression is a reference to the newly created object of the specified class. Every time the expression is evaluated, a fresh object is created.

A constructor therefore can never return null. However, an java.lang.OutOfMemoryError may occur.

score 1 · Answer 3 · answered May 15 '13 at 07:42

1

new never results in null, yes.

answered May 15 '13 at 07:42

Sean Owen

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score 1 · Answer 4 · answered May 15 '13 at 07:44

1

Yes, it can never be null. why do you doubt?

answered May 15 '13 at 07:44

vishal_aim

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I doubted because the code explicitly checked for it, and I couldn't find that part of the spec where it was explicitly stated this was a useless check. – Anders Johansen May 15 '13 at 08:06

Can new Double(String) ever return a null?

4 Answers4