如何将参数/参数传递给回调 function？

Question

A naive question as I am a bit new to programming. I am Working on an Android application where I need to pass parameters to the callback method(Not sure if the verbiage is right).

I want the parameters/variables to be available to the Main Function. I am calling the Caller to invoke my main function and hence need the parameters to pass from the Caller.

something like the classic functions does

Example

method(param1, param2);

function method(param1, param2){
    Log(param1 + param 2);
      ....
}

I need the below code to achieve the functionality as the above example

the code is as follows:

//Caller:- 
 getChioceList(new MyCallback() {
                @Override
                public void onCallback(ArrayList<String> value) {
                Log.d("TAG", "Config CallBack " + value);
                }
});

//Interface
public interface MyCallback{
    void onCallback(ArrayList<String> value);
}

//Main function: I want some parameters to be passed to this method

 public void getChioceList(final MyCallback myCallback) {
     final ArrayList < String > result = new ArrayList < > ();
     final DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
     Query query = ref.child("Device").orderByChild("home").equalTo(homeID);
     query.addListenerForSingleValueEvent(new ValueEventListener() {

         @Override
         public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

             for (DataSnapshot dataSnapshots: dataSnapshot.getChildren()) {
                 result.add(dataSnapshots.getKey());
                 Log.i(TAG, "Config: get Input 3 " + result);
             }
             myCallback.onCallback(result);
         }

         @Override
         public void onCancelled(@NonNull DatabaseError databaseError) {}
     });
 }

Please help...

Answer 1

Based on what i understand. Basically you want to pass something to a callback method.

I would suggest to create another class that will implement ValueEventListener .

Like so

public class SomeClassThatWillImplement implements ValueEventListener {

    private String cVar1;
    private String cVar2;

    public SomeClassThatWillImplement (String param1, String parma2) {
        this.cVar1 = param1;
        this.cVar2 = param2;
    }

    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

        //Do something with this.cVar1
        //Do something with this.cVar2
        for (DataSnapshot dataSnapshots : dataSnapshot.getChildren()) {
            result.add(dataSnapshots.getKey());
             Log.i(TAG, "Config: get Input 3 " + result);
        }
        myCallback.onCallback(result);
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        //Do something with this.cVar1
        //Do something with this.cVar2
    }

}

To use above class,

public void getChioceList(final MyCallback myCallback) {
    final ArrayList<String> result = new ArrayList<>();
    final DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
    Query query = ref.child("Device").orderByChild("home").equalTo(homeID);
    query.addListenerForSingleValueEvent(new SomeClassThatWillImplement(param1, param2));
}

Hopefully this helps