How to convert double to object?

Question

I am writing part of my program which read data from a txt file.

I have problem when I want to set value of JSpinner by setValue(object).

My data is double so I need to convert it to object, but how?

LoadData open = new LoadData();
data.setFz(open.giveAwayData());
spinner_1.setValue(data.getFz()); // Fz is double

I've just tried it and I can use a double as the argument, with no casts nor conversions ;) — eric.m, Aug 29 '15 at 19:15
Unfortunately, it's not as weird a bug as you think. Eclipse has a tendency to lose its mind every now and then, and you have to restart. It happens far too often. You just have to get used to it (like I do), or switch to IntelliJ (which I hear is a little more stable, but I'm not sure). — ajb, Aug 29 '15 at 23:41

colouredmirrorball · Answer 1 · 2015-08-29T19:16:28.137

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Try casting it to Double (with capital):

spinner_1.setValue((Double) data.getFz());

edited Aug 29 '15 at 19:16

answered Aug 29 '15 at 19:11

colouredmirrorball

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If this is an answer, it shouldn't end with a question mark. :) Also, showing the code would be really helpful. I think this is the right answer, but you just need a little more to make it a good answer. – ajb Aug 29 '15 at 19:13
Ideally this would be a comment but I can't comment yet so deal with it. But I'll edit it as to your suggestions. – colouredmirrorball Aug 29 '15 at 19:15
I dont understand what mean with capital. Give some code, please. – Xalion Aug 29 '15 at 19:18
@Xalion "capital" means upper-case. Java distinguishes between `double`, which is a primitive type and not an object, and `Double`, which is an object. `Double` begins with an upper-case (capital) D. Often Java will automatically convert between the two (boxing and unboxing). – ajb Aug 29 '15 at 19:21
spinner_1.setValue((Object) data.getFz()); it should look like that, but it doesnt work. – Xalion Aug 29 '15 at 19:51
@Xalion Does your IDE specifically say that it's the wrong parameter type? If so, your method doesn't _actually_ have a parameter typed `Object` at all. Otherwise, you must be mistaking which bit of your code is erroneous. – bcsb1001 Aug 29 '15 at 19:58
@bcsb1001 The parameter type is `Object`; I looked up `JSpinner` to confirm this. Apparently the IDE had lost its mind. – ajb Aug 29 '15 at 23:39

score 3 · Answer 2 · edited May 23 '17 at 12:17

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Use Double.valueOf(data.getFz()). An explanation of the differences between primitives and boxed primitives can be found here; basically, primitives have better performance but the boxed classes are there for when you need an Object. A common example is with generics, which cannot be primitives.

However, a double can be passed to something requiring a Double or one of its superclasses. This is because of autoboxing. Yes, I like links a lot.

edited May 23 '17 at 12:17

Community

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answered Aug 29 '15 at 19:19

bcsb1001

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it doesnt work... i need OBJECT, not double. it is setValue(object) – Xalion Aug 29 '15 at 19:52
Like I said, autoboxing should solve that problem for you. Also, `Double` is a subclass of `Object`. But you can always use `Object obj = data.getFz();` (autoboxing lets that work). – bcsb1001 Aug 29 '15 at 19:53
Never use `new Double`. Always use [Double.valueOf](https://docs.oracle.com/javase/8/docs/api/java/lang/Double.html#valueOf-double-) instead. – VGR Aug 29 '15 at 19:57
@VGR, yeah, forgot that was in `Double` too. – bcsb1001 Aug 29 '15 at 19:59

score 2 · Answer 3 · answered Aug 29 '15 at 19:14

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You can use for example the Double constructor to convert double primitive type to a Double object.

Double dObj = new Double(d);

or you can cast it to Double like this:

spinner_1.setValue((Double)data.getFz());

answered Aug 29 '15 at 19:14

Rahul Tripathi

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Why do you need a cast? Or explicit Double creation? Autoboxing should take care of it right... – Codebender Aug 29 '15 at 19:23
@Codebender:- Indeed! `new Double(data.getFz())` is fine. – Rahul Tripathi Aug 29 '15 at 19:24
it is setValue(object). I need object inside... how to set number... it should be easy. – Xalion Aug 29 '15 at 19:53
@Xalion:- You can try: `setValue(((Number)object).doubleValue())` – Rahul Tripathi Aug 29 '15 at 19:57

How to convert double to object?

3 Answers3

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