How to get the key of the vale in json simple in java

Question

I encountered a problem

{
"a": "X1abs",
"b": "d4vT"

}

This is to be done with plugin json-simple

So what I want is that if I have "X1abs", then I get the key which is "a" Please Help me

Answer 1

Below code convert JSON to map

public static Map<String, Object> jsonToMap(JSONObject json) throws JSONException {
    Map<String, Object> retMap = new HashMap<String, Object>();
    
    if(json != JSONObject.NULL) {
        retMap = toMap(json);
    }
    return retMap;
}

public static Map<String, Object> toMap(JSONObject object) throws JSONException {
    Map<String, Object> map = new HashMap<String, Object>();

    Iterator<String> keysItr = object.keys();
    while(keysItr.hasNext()) {
        String key = keysItr.next();
        Object value = object.get(key);
        
        if(value instanceof JSONArray) {
            value = toList((JSONArray) value);
        }
        
        else if(value instanceof JSONObject) {
            value = toMap((JSONObject) value);
        }
        map.put(key, value);
    }
    return map;
}

public static List<Object> toList(JSONArray array) throws JSONException {
    List<Object> list = new ArrayList<Object>();
    for(int i = 0; i < array.length(); i++) {
        Object value = array.get(i);
        if(value instanceof JSONArray) {
            value = toList((JSONArray) value);
        }

        else if(value instanceof JSONObject) {
            value = toMap((JSONObject) value);
        }
        list.add(value);
    }
    return list;
}

Below code identify the key based on the value:

for (Entry<Integer, String> entry : testMap.entrySet()) {
            if (entry.getValue().equals("c")) {
                System.out.println(entry.getKey());
            }
        }

Answer 2

If the value like “X1abs” is unique, then you could create a reverse map to store the value as the key, and the key as the value. Example like this:

Create a HashMap:

Map<String, String> reverseMap = new HashMap<>();

Then, for each object key : value, you do so:

reverseMap.put(value, key);

After you finalize the map, you could retrieve your key with the value, something like this:

String key = reverseMap.get(“X1abs”); // the key should be “a”

However, if the value is not unique, there is no unique solution on the key. You need a list of keys for each value, the map should be like this:

Map<String, List<String>> reverseMap = new HashMap<>();

Then, for each object (value, key) you do so:

reverseMap.computeIfAbsent(value, x -> new ArrayList<>()).add(key);

After the map is finalized, for each value you could retrieve a list of keys:

List<String> list = reverseMap.get(“X1abs”);

You can then iterate the list to get whatever value you want.