Can't retrieve ID's

If my xml file (shown below as sample) has different employees with id's - is there a way I can get just the id's on there own?

Java Code:

<Employees>  
    <Employee id="1">  
        <age>29</age>  
        <name>Pankaj</name>  
        <gender>Male</gender>  
        <role>Java Developer</role>  
    </Employee>  
    <Employee id="2">  
        <age>35</age>  
        <name>Lisa</name>  
        <gender>Female</gender>  
        <role>CEO</role>  
    </Employee>  
</Employees>

This is the code Im using - I know at the minute it gets the id details of id 3 but realistically I just want the id's and nothing else

Java Code:

 private static String getEmployeeById(Document doc, XPath xpath, int id) {  
        String env = null;  
        try {  
            XPathExpression pathExpression =  
                    xpath.compile("/Employees/Employee[@id=3]"); // line gets everything to do with id 3 but doesnt display the id - I need it to display all the id's  
            env = (String) pathExpression.evaluate(doc, XPathConstants.STRING);  
        } catch (XPathExpressionException e) {  
            e.printStackTrace();  
        }  
  
        return env;  
    }

Can this be achieved using xpath? I've been stuck on it for ages and I can't seem to really find anything to do with it