I have a List(fruits) that I want to find and print the reference(memory address) of it, How can I?
val fruits:List[String]=List("apple","orange","pear")
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sahar karimzadeh
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4WDYM with the _"references"_ of it? – Luis Miguel Mejía Suárez Nov 22 '21 at 22:10
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The reference of the fruits Object @LuisMiguelMejíaSuárez – sahar karimzadeh Nov 22 '21 at 22:49
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Still, I don't understand, WDYM with the references of the fruits objects? Do you mean their memory addresses? – Luis Miguel Mejía Suárez Nov 22 '21 at 22:58
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Yes, I mean the memory address of fruit or any other collection. – sahar karimzadeh Nov 23 '21 at 20:52
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Well, AFAIK, you can't get the memory address of an object. Why do you want to get that? What is the meta-problem you are trying to solve? – Luis Miguel Mejía Suárez Nov 23 '21 at 21:04
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Based on this [link](https://stackoverflow.com/questions/8287425/mutable-vs-immutable-in-scala-collections) and last comment of it, I was trying to test this sentences:"Each time you modify an immutable collection, another collection is produced instead of modifying the original collection in-place." – sahar karimzadeh Nov 26 '21 at 16:34
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Well, you don't need the memory address for that. You can just do `list1 eq list2` check the **Scaladoc**: https://www.scala-lang.org/api/current/scala/AnyRef.html#eq(x$1:AnyRef):Boolean – Luis Miguel Mejía Suárez Nov 26 '21 at 16:48
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Thank you, do you know what is the reason that we can't get the memory address of an object In Scala? @LuisMiguelMejíaSuárez – sahar karimzadeh Nov 29 '21 at 13:39
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Because the underlying runtime _(the JVM)_ doesn't provide that; which makes sense since the data can be moved into different memory positions automatically. – Luis Miguel Mejía Suárez Nov 29 '21 at 14:44
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Garbage collector in Scala and Java is the same, do you know why Scala behaves different from Java in this case? – sahar karimzadeh Nov 29 '21 at 14:54
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It doesn't, it behaves exactly the same. That is the point I just made. The runtime system doesn't allow you to get memory addresses because it doesn't have any guarantee over those. You can't get them either in **Java**. – Luis Miguel Mejía Suárez Nov 29 '21 at 14:57
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As I know, based on [this](https://www.baeldung.com/java-object-memory-address#memory-address) we can catch the memory of object in Java, even in runtime, But, as you say, I couldn't do the same in Scala? Right? @LuisMiguelMejíaSuárez – sahar karimzadeh Nov 29 '21 at 15:31
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Yeah, you can, but again remember that value may be outdated as for the moment you print. – Luis Miguel Mejía Suárez Nov 29 '21 at 17:22
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It is not really clear what you mean by references. A String is already A reference. If you want to unrefine it ("forget" that the underlying structure is a String) and just have a pure reference you can rely on the fact that the type parameter of a list if covariant and List[String] is a subtype of List[AnyRef].
val refs: List[AnyRef] = fruits
Not sure why this would be useful tho. Not much you can do with references.
Navid Jalali
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It is impossible to get an address of any primitive variable or object on the JVM. The closes thing is the object hashcode with System.identityHashCode(a). which is related to its address, but there are no guarantees here. – Navid Jalali Dec 05 '21 at 02:28
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Ok, I mean Something like this case in Java, That it is the memory reference in a specific time, Can I have it? Is System.identityHashCode(a) something like that? – sahar karimzadeh Dec 09 '21 at 06:02