primefaces selectOneMenu未排序

Question

I have a selectonemenu in my page and i get its contents from my backing bean. But contents of selectonemenu is not sorted.Here is the code...

    <p:selectOneMenu id="Department" value="#{search.selectedDepartment}">  
            <f:selectItem itemLabel="Select Department" itemValue="" />  
            <f:selectItems value="#{search.departments}" />  

        </p:selectOneMenu> 

and my bean...

public class SearchBean implements Serializable {

private Map<String, Map<String, String>> courseData = new HashMap<String, Map<String, String>>();

private Map<String, String> departments = new HashMap<String, String>();
private String selectedDepartment;


    departments.put("department1",
            "department1");
    departments.put("department2",
            "department2");
    departments.put("department3", "department3");
departments.put("department4", "department4");
departments.put("department5", "department5");





//getters setters...


}

and contents of selectonemenu is not department1,department2,department3,department4,department5 respectively.It is not sorted.

Answer 1

It's not sorted because HashMap doesn't have a predictable iteration order. Try LinkedHashMap instead.

Answer 2

使用LinkedHashMap时 ，不排序，即按放置项目的顺序获得它，但如果使用TreeMap ，则按字母顺序排序