Android java enumerate JSONObject child items code

1.what

i need enumerate the JSONObject child item key and value by code

2.how

            JSONObject obj = null; // please set this not null value in first


            Iterator<String> k = obj.keys();
            String key;
            Object value;
            while(k.hasNext()){
                key = k.next();
                value = obj.opt(key);
                if(value == null || obj.isNull(key))
                    continue;
                
                if(value instanceof JSONArray){
                    JSONArray jary = (JSONArray)value;
                    
                }else if(value instanceof JSONObject){
                    JSONObject jobj = (JSONObject)value;
                    
                }else if(value instanceof String){
                    String s = (String)value;
                    
                }else if(value instanceof Long){
                    Long l = (Long)value;
                    
                }else if(value instanceof Integer){
                    Integer l = (Integer)value;
                    
                }else if(value instanceof Boolean){
                    Boolean b = (Boolean)value;
                    
                }else if(value instanceof Double){
                    Double d = (Double)value;
                }
            }

3.Last:

Thanks!