如何在 java 脚本中使用树形图

Question

I am sending one treemap from java servlet to jsp. I am able to use the treemap keys as drop down list inside jsp page. My map contains country name as key and capital as value when user selected country name i just need to display country capital in the text box.I need selected key value(country name) in the java page after form submission(I know hot to do this).when i am reading map from java script it is taking as string/[object Object]. how can i use map.get(key) here. Thanks in advance

function fillText(obj)
    {
               
               var key= obj.options[obj.selectedIndex].value;
           var map = new Map('<%=request.getAttribute("countrylist")%>');
           
           var contract = "${countrylist}";
           
           
    }
    <label for="Select The Switch">Select The Switch:</label>
           <select name="country" id="countrycode"  onchange="fillText(this)" required>
           <option value= "" >Please select the switch</option>
        <c:forEach items="${countrylist}" var="countrylist">
        <option value=${countrylist.key}>${countrylist.key}</option>
        </c:forEach>
       
            </select>`)  
    Country capital:<input type="text" id="pass" readonly >

Answer 1

Finally, I found the answer myself.I have converted treemap to json object in the servlet class and pushed to jsp

Servelt java

Gson gson = new Gson();
String json=gson.toJson(countrylist);
request.setAttribute("json", json);

javascript function

function fillText(obj)
{
           
                  var key= obj.options[obj.selectedIndex].value;
                      var json=${json};
                  var value=json[key]
                  document.getElementById("pass").value=value;
                  
}

import gson-2.8.0.jar to the class path. It works fine for me, not sure it is a right way.