Java Class that implements Map and keeps insertion order?

Question

I'm looking for a class in java that has key-value association, but without using hashes. Here is what I'm currently doing:

1. Add values to a Hashtable.

2. Get an iterator for the Hashtable.entrySet().

3. Iterate through all values and:

   1. Get a Map.Entry for the iterator.

   2. Create an object of type Module (a custom class) based on the value.

   3. Add the class to a JPanel.

4. Show the panel.

The problem with this is that I do not have control over the order that I get the values back, so I cannot display the values in the a given order (without hard-coding the order).

I would use an ArrayList or Vector for this, but later in the code I need to grab the Module object for a given Key, which I can't do with an ArrayList or Vector.

Does anyone know of a free/open-source Java class that will do this, or a way to get values out of a Hashtable based on when they were added?

Thanks!

Answer 1

LinkedHashMap will display the values in the order they were inserted into the map when you iterate them over the keySet(), entrySet() or values() of the map.

Map<String, String> map = new LinkedHashMap<String, String>();

map.put("id", "1");

map.put("name", "rohan");

map.put("age", "26");

for (Map.Entry<String, String> entry : map.entrySet()) {

    System.out.println(entry.getKey() + " = " + entry.getValue());

}

This code will return the values in the order they were put into the map:

id = 1

name = rohan 

age = 26 

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