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Thread: How to use an ArrayList and what is its advantage over array?

  1. #1
    mmm.. coffee JavaPF's Avatar
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    Post How to use an ArrayList and what is its advantage over array?

    A lot of people ask me how to use an ArrayList and also ask what is the advantage of an ArrayList over a standard Array.

    If the data has a known number of elements or small fixed size upper bound, arrays are often the best choice. However, many data storage problems are not that simple. The main advantage to an ArrayList is that it automatically expands as data is added. A disadvantage is that an ArrayList cannot work with primitive types.

    Here is a quick example to show you how to add, print, and remove data from an ArrayList:

    // Import ArrayList
    import java.util.ArrayList;
     
    public class ArrayListExample {
     
        /**
         * JavaProgrammingForums.com
         */
        public static void main(String[] args) {
     
            // Construct a new empty ArrayList for type String
            ArrayList<String> al = new ArrayList<String>();
     
            // Fill ArrayList (index, String)
            al.add(0, "Java");
            al.add(1, "Programming");
            al.add(2, "Forums");
            al.add(3, ".com");
     
            // Convert ArrayList to Object array
            Object[] elements = al.toArray();
     
            // Print Object content
            for (int a = 0; a < elements.length; a++) {
                System.out.println(elements[a]);
            }
     
            // Remove item from ArrayList
            al.remove(3);
     
            // Clear entire ArrayList
            al.clear();
        }
     
    }
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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  2. The Following 2 Users Say Thank You to JavaPF For This Useful Post:

    ShaunB (October 25th, 2011), xmode (November 22nd, 2012)


  3. #2
    Member Fendaril's Avatar
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    Default Re: How to use an ArrayList - java.util.ArrayList

    You forgot to add that ArrayLists cannot work with primitive types.

  4. The Following 2 Users Say Thank You to Fendaril For This Useful Post:

    JavaPF (May 17th, 2009), xmode (November 22nd, 2012)

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    Default Re: How to use an ArrayList - java.util.ArrayList

    thanks alot
    it is working

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    Default

    Old but very good tutorial.

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    Default Re: How to use an ArrayList - java.util.ArrayList

    Quote Originally Posted by JavaPF View Post
    A disadvantage is that an ArrayList cannot work with primitive types.
    It works since Java 5 via autoboxing/unboxing feature. This understand is old and should be replaced.

    Spring 3
    Last edited by cafeteria84; January 22nd, 2012 at 03:06 PM.

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