How to cast IssueField.getValue() in JIRA Java REST API (m31)

Here is the code:

IssueField field = issue.getField(id);
field.getValue() returns an Object
how to I cast it if the custom field is selection (drop-down list), radio buttons, etc?
I tried to cast it to FieldInout, CustomFieldOption, etc. all failed.

field.getValue().toString() will produce something like:

  1. Object(?):
    {“self”:“http://172.26.21.151:8080/ncijira/rest/api/2/customFieldOption/10109",“value”:“Delaware”,“id”:"10109”}
  2. Array of Objects (?):
    [{“self”:“http://172.26.21.151:8080/ncijira/rest/api/2/customFieldOption/10125",“value”:"Aircraft Noise”,“id”:“10125”}]
    =============================================
    My goal is to get the value of the custom field. Later I may need to update the value.

Thanks in advance for help!