Why is my BigDecimal 0.0000 not equal to BigDecimal.ZERO?

Question

I've got the following expression in Android Java:

myVar + " == 0 ? " + BigDecimal.ZERO.equals(myVar)

which outputs the following:

0.0000 == 0 ? false

Where myVar is declared as:

public BigDecimal myVar;

And assigned successfully with Gson, from served JSON data (I inspected this to verify the JSON was good). Why does 0.0000 as a BigDecimal not equal BigDecimal.ZERO?

But please post the code that initializes/sets the value for `myVar`. — Mick Mnemonic, Jul 28 '15 at 22:39
`myVar` is assigned from our custom JSON deserializer. "All relevant code" will end up being thousands of lines that you wouldn't want to read even if I was allowed to disclose it. Long story short: it is successfully converted from a JSON `0.0000` to an Android Java `BigDecimal` `0.0000`. — Ky -, Jul 28 '15 at 22:49
Duplicate of http://stackoverflow.com/questions/3866514/why-bigdecimal5-50-not-equals-to-bigdecimal5-5-and-how-to-work-around-th — Alexis C., Jul 29 '15 at 23:26

score 5 · Accepted Answer · edited Dec 26 '18 at 19:59

5

From the documentation:

Returns true if x is a BigDecimal instance and if this instance is equal to this big decimal. Two big decimals are equal if their unscaled value and their scale is equal. For example, 1.0 (10*10^-1) is not equal to 1.00 (100*10^-2). Similarly, zero instances are not equal if their scale differs.

Why did they decide this? Probably because its easier to implement. Is it a good decision? I don't think so, but it is what it is. Use another library if you don't like it.

edited Dec 26 '18 at 19:59

Ky -

30,724
51
192
308

answered Jul 28 '15 at 22:42

Gabe Sechan

90,003
9
87
127

2

This makes me want to extend `BigDecimal` and add methods like `equalsIgnoreScale` – Ky - Jul 28 '15 at 22:44

score 3 · Answer 2 · edited Mar 12 '20 at 20:02

3

One solution given in an answer to another similar question is to use compareTo. So, you could change your code to

myVar + " == 0 ? " + (BigDecimal.ZERO.compareTo(myVar) == 0)

edited Mar 12 '20 at 20:02

Ky -

30,724
51
192
308

answered Mar 12 '20 at 00:20

Baptiste Pernet

3,318
22
47

Why is my BigDecimal 0.0000 not equal to BigDecimal.ZERO?

2 Answers2