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Thread: URGENT Array List Question

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    Default URGENT Array List Question

    Suppose that you have an ArrayList and that it contains String objects.
    Which declaration of the ArrayList requires that objects retrieved using the
    get method be cast to Strings before calling a String method?

    I. ArrayList a = new ArrayList();
    II. ArrayList<Object> a = new ArrayList<Object>;
    III. ArrayList<String> a = new ArrayList<String>;

    A. I only
    B. II only
    C. III only
    D. I and II only
    E. I, II, and III


    I really have no idea on this question. I know that all of these are ways to declare an Array List, but I am unfamiliar with the last two since I usually just declare my Array Lists with the first option.


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    Default Re: URGENT Array List Question


  3. The Following User Says Thank You to copeg For This Useful Post:

    iWaterBuffalo (May 5th, 2014)

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    Default Re: URGENT Array List Question

    Okay, so I know that I is definitely correct. So that brings me down to A or D. Would <Object> behave the same as <String>?

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    Default Re: URGENT Array List Question

    Your last question is a good one. If the answer is not obvious after about 15 seconds of thought, you could write a simple program to see if calling a String method with an Object is the same as calling a String method with a String instance.

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    iWaterBuffalo (May 5th, 2014)

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    Default Re: URGENT Array List Question

    Thank you both. I figured out the correct answer.

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    Default Re: URGENT Array List Question

    Only III is correct. Even though you may use I & II to create a String ArrayList, you still need to cast them before using.

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    Default Re: URGENT Array List Question

    Quote Originally Posted by PitLv View Post
    Only III is correct. Even though you may use I & II to create a String ArrayList, you still need to cast them before using.
    Is that your final answer?

    Which declaration of the ArrayList requires that objects retrieved using the
    get method be cast to Strings before calling a String method?

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