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  1. #1
    toby is offline Member
    Join Date
    Jul 2007
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    Default Help with HashMap in java

    I have a hashmap setup in the following way:
    Java Code:
    Key Value
    0 XXX
    1 XYX
    2 XYY
    3 XXX
    4 YXX
    5 YXX
    I currently can check if a given value is in the map no problem. But once I determine that a value is in the map, how do I return the key or keys at which a given value was found? This is crucial for me to be able to do. I know values are not unique but there has to be a way to return which key or keys have that value.

  2. #2
    Seemster is offline Member
    Join Date
    Jul 2007
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    // Create a hash table
    Map map = new HashMap(); // hash table
    map = new TreeMap(); // sorted map

    // Add key/value pairs to the map
    map.put("a", new Integer(1));
    map.put("b", new Integer(2));
    map.put("c", new Integer(3));

    // Get number of entries in map
    int size = map.size(); // 2

    // Adding an entry whose key exists in the map causes
    // the new value to replace the old value
    Object oldValue = map.put("a", new Integer(9)); // 1

    // Remove an entry from the map and return the value of the removed entry
    oldValue = map.remove("c"); // 3

    // Iterate over the keys in the map
    Iterator it = map.keySet().iterator();
    while (it.hasNext()) {
    // Get key
    Object key =;

    // Iterate over the values in the map
    it = map.values().iterator();
    while (it.hasNext()) {
    // Get value
    Object value =;

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