I have a Java hashmap with a a list of a groups:
private HashMap<String, String> listGroups = new HashMap<>();
The question is how I can display the values from the hashmap into the selectonemenu?
BalusC
The <f:selectItems> already supports maps.
<f:selectItems value="#{bean.listGroups}" />
The map key becomes the option label and the map value becomes the option value.
That said, you probably want to use LinkedHashMap instead of HashMap if displaying the map entries in insertion order is important, or TreeMap if you want to automatically sort them by map key.
See also
来源：https://stackoverflow.com/questions/11484126/how-to-display-hashmap-in-jsf-using-selectonemenu