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Thread: Please help ArrayList Question

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    Default Please help ArrayList Question

    Declare an ArrayList named taxRates of * five *elements of type Double and initialize the elements (starting with the first) to the values 0.10 , 0.15 , 0.21 , 0.28 , 0.31 , respectively.


    I tried:

    double taxRates[5] = {0.10, 0.15, 0.21, 0.28, 0.31};


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    Default Re: Please help ArrayList Question

    That's an array, not an ArrayList.
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    Default Re: Please help ArrayList Question

    What does that mean?

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    Default Re: Please help ArrayList Question

    An ArrayList is an Object that holds a variable amount of other Objects.

    An array is a container that holds a fixed number of Objects or primitives.

    They aren't the same, and what you've supplied doesn't match your title, so some clarification is necessary.
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    Default Re: Please help ArrayList Question

    Additional to Kevin's answer: Well, in easy words though
    1. Arrays are non resizable
    2. Arrays store only single data type values(Say Elements).
    3. ArrayLists are resizable.
    4. ArraLists can store multi data type values(Say Objects).

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    Default Re: Please help ArrayList Question

    Quote Originally Posted by Mr.777 View Post
    Additional to Kevin's answer: Well, in easy words though
    1. Arrays are non resizable
    2. Arrays store only single data type values(Say Elements).
    3. ArrayLists are resizable.
    4. ArraLists can store multi data type values(Say Objects).
    I just woke up and I haven't tested this, but couldn't you store multiple types in an array by doing something like this:

    Object[] objs = {new Object(), "cats", 7};
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    Default Re: Please help ArrayList Question

    Well, arrays of primitive types, not of some defined objects.

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    Default Re: Please help ArrayList Question

    Quote Originally Posted by Mr.777 View Post
    Well, arrays of primitive types, not of some defined objects.
    I'm still not sure I agree with that. Arrays definitely can contain primitives (whereas ArrayLists can only contain Objects, including wrapper classes for primitives). But arrays can also contain Objects, like I showed above, right?
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    Default Re: Please help ArrayList Question

    Quote Originally Posted by KevinWorkman View Post
    I'm still not sure I agree with that. Arrays definitely can contain primitives (whereas ArrayLists can only contain Objects, including wrapper classes for primitives). But arrays can also contain Objects, like I showed above, right?
    int [] arr = new int[10];
    What do you say about this?

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    Default Re: Please help ArrayList Question

    Quote Originally Posted by Mr.777 View Post
    int [] arr = new int[10];
    What do you say about this?
    Like I said, arrays definitely CAN contain primitives, but they don't HAVE to. They con contain Objects as well. So to say the can only contain a single data type is not correct. I don't want to be pedantic, but the OP seems extremely confused already, so I don't want to confuse him even more.
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  12. The Following User Says Thank You to KevinWorkman For This Useful Post:

    Mr.777 (November 14th, 2011)

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    Default Re: Please help ArrayList Question

    Oh yeah if this is the fact then yes arrays can have multiple types. So, ignore the point, Arrays can store only single type elements.

    So Kevin, don't you think, elements and objects are different things?

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    Default Re: Please help ArrayList Question

    Quote Originally Posted by Mr.777 View Post
    Oh yeah if this is the fact then yes arrays can have multiple types. So, ignore the point, Arrays can store only single type elements.

    So Kevin, don't you think, elements and objects are different things?
    It depends what you mean by "elements". Objects can be elements in an array or an ArrayList. But if you mean "primitives" instead of "elements" then yeah, Objects and primitives are different.
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    Default Re: Please help ArrayList Question

    Yes that is fine. What Kevin is questioning is the following statement made by you:

    2. Arrays store only single data type values

    Which is incorrect! Arrays can most certainly hold elements of different data types as long as they are subclasses of a superclass. Just as Kevin demonstrated above

    Bah! Page 2.
    Improving the world one idiot at a time!

  16. The Following 2 Users Say Thank You to Junky For This Useful Post:

    KevinWorkman (November 15th, 2011), Mr.777 (November 14th, 2011)

  17. #15
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    Default Re: Please help ArrayList Question

    Alright Kevin. Thanks. Well, atleast i got some new knowledge coz of you.
    Thanks alot.
    Thanks Junky.

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