React native communication between React native and android with custom object

Question

I have a react native component that communicates with Android like this -

My React Native code-

const myModule = NativeModules.MyProcessor;

myModule.processData(obj1, obj2);

My Android code in MyProcessor.java is -

@ReactMethod
    public void processData(final Object1 obj1, final Objet2 obj2) {
        //Do something here
    }

My object data looks like -

"data1": {
                "id": "1",
                "name": "john",
                "key": "xxxxxxxx"
            },
            "details": {
                "detailId": "2",
                "detailName": "peter",
                "counter": 1
            }

I get the 2 objects data1 and details out of which I need both and also detailId.

My question is how do I use these 2 objects in my java?

Answer 1

Question:

How do I use these 2 objects Object1 and Object2 in my java?

Answer: Quoted from here:

"The following argument types are supported for methods annotated with @ReactMethod and they directly map to their JavaScript equivalents"

Boolean -> Bool
Integer -> Number
Double -> Number
Float -> Number
String -> String
Callback -> function
ReadableMap -> Object
ReadableArray -> Array

React Native is converting the javascript object into a ReadableMap.

So instead of expecting an Object in the native module, You should implement the method like this:

@ReactMethod
public void processData(final ReadableMap obj1, final ReadableMap obj2) {
    // Parse the ReadableMap using the available interface methods
}

Those are the available methods in the ReadableMap interface: Source

public interface ReadableMap {

  boolean hasKey(String name);
  boolean isNull(String name);
  boolean getBoolean(String name);
  double getDouble(String name);
  int getInt(String name);
  String getString(String name);
  ReadableArray getArray(String name);
  ReadableMap getMap(String name);
  Dynamic getDynamic(String name);
  ReadableType getType(String name);
  ReadableMapKeySetIterator keySetIterator();
  HashMap<String, Object> toHashMap();
}

UPDATE

Following the example object you posted, you can parse your data like this:

ReadableMap data1 = obj1.getMap("data1");
String id = data1.getString("id");
String name = data1.getString("name");
// And so on...

ReadableMap details = obj1.getMap("details");
String detailId = details.getString("detailId");
int counter = details.getInt("counter");
// And so on...

Answer 2

If you want to pass complex objects from React-Native to Android, you should use ReadableMap, which is used in JavaScript bridge and equivalent to a HashMap.

ReadableMap obj1

Then, you can cast this to a HashMap and easily get the values

HashMap map = (HashMap) obj1;
String field = map.get("key").toString();

For the specific values you provided:

Get data1 as another HashMap from obj1:

HashMap details = (HashMap) map.get("details");

Read strings from details map:

String detailId = details.get("detailId").toString();

Answer 3

Send Map or object from react native to android native

 const yourMap = { "param1": "value1",
        "param2": "value2",

        };
        const strValue = "hello";
        MainModule.methodName(strValue, yourMap)

Receive in android side

 @ReactMethod
    fun methodName(
        strValue: String,
        info: ReadableMap,
        promise: Promise
    ) {
        mPickerPromise = promise
        var hashmap = Utils.toHashMap(info)
        // do your stuff here

    }

Where Utils.toHashMap()

fun toHashMap(map: ReadableMap?): HashMap<String, Any?> {
    val hashMap: HashMap<String, Any?> = HashMap()
    val iterator = map!!.keySetIterator()
    while (iterator.hasNextKey()) {
        val key = iterator.nextKey()
        when (map.getType(key)) {
            ReadableType.Null -> hashMap[key] = null
            ReadableType.Boolean -> hashMap[key] = map.getBoolean(key)
            ReadableType.Number -> hashMap[key] = map.getDouble(key)
            ReadableType.String -> hashMap[key] = map.getString(key)
            ReadableType.Map -> hashMap[key] = toHashMap(map.getMap(key))

            else -> throw IllegalArgumentException("Could not convert object with key: $key.")
        }
    }
    return hashMap
}