To be even more specific, I wish to access the Map as I iterate over a List of objects, e.g.,

#{list items:itemList, as:'item'} // access the map value using the ${item?.id} as the key #{/list}

but how to use Map like HashMap, TreeMap to play framework template?

This is a  generic solution  to iterate on Map in using Play! Framework:

in the controller :

render(map);

in the template:

#{list items:map.keySet(), as:'key'} ${map.get(key)} #{/list}

 

The fact that you want to rely on a side List to iterate on your Map suggest me that you are searching a predictible way for your iteration process.

In that case, just remember that iteration will be unpredictable if you don’t use an ordered/sorted _Map_implementation.

 

  • HashMap  gives you an  unsorted ,  unordered  Map
  • LinkedHashMap  maintains  insertion order
  • TreeMap  is the only JDK implementation of a  sorted  Map. By default it allows you to iterate following the  natural order  of the elements. You can also specify a custom sort order and implements the Comparable interface. This will lead you to override the compareTo() method.