HashMap


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Thread: HashMap

  1. #1
    Join Date
    Oct 2003
    Posts
    2

    Arrow HashMap

    Hi,
    i'm trying to edit a hashmap in a method, i can get it to return the non-key value (using get() ) but it returns it as an object and i'm strugling to convert in into an integer to edit it. I don't know if i'm being an idiot (more then likely ) or not.

    If anyone could help i'd be very grateful

    Andy

  2. #2
    Join Date
    Mar 2003
    Posts
    834
    You need to cast objects can come out of HashMap:
    Code:
    import java.util.Map;
    import java.util.HashMap;
    
    public class Test {
            public static void main(String[] args) {
                    Map myMap = new HashMap(); // Program by interfaces.
                    myMap.put("One", new Integer(1));
                    myMap.put("Two", new Integer(2));
                    Integer associatedWithOne = (Integer)myMap.get("One"); // Note the cast
                    Integer associatedWithTwo = (Integer)myMap.get("Two"); // Note the cast
                    System.out.println(associatedWithOne);
                    System.out.println(associatedWithTwo);
            }
    }
    It seems a little strange to begin with, but you soon get used to it (the next version of Java will make this much nicer).

    Note - you can't put primitives (int, char, long) directly into a HashMap, you have to put them in 'wrapper' classes (Integer, Character, Long).
    ArchAngel.
    O:-)

  3. #3
    Join Date
    Oct 2003
    Posts
    2
    ok cheers for that, got one error less now

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