GWT : compilation error with Map

Problème :

         In your code, you declare Map<Integer, Integer> map = new HashMap<Integer, Integer>

and you have the following error  :

         [ERROR] Line 23: No source code is available for type com.google.gwt.dev.util.collect.HashMap<K,V>; did you forget to inherit a required module?

Solution :

Map collections works with Object.However Object isn't serializable.So to work, you have to pass the following arguments in comments :@gwt.typeArgs <java.lang.Integer,java.lang.Integer>

to define the contents of your map :

public class ChartData implements IsSerializable {

  /**

   * This field is a Map that must always contain Strings as its keys and

   * values.

   * 

   * @gwt.typeArgs <java.lang.Integer,java.lang.Integer>

   */

  public Map data;

  

  public ChartData() {

  }

}

Then you can use your Map like that :

CharData charData = new CharData();

charData.data.put(12,13);

Ref :

http://www.gwtapps.com/doc/html/com.google.gwt.doc.DeveloperGuide.RemoteProcedureCalls.SerializableTypes.html