我想將數據活動發送到片段但從未調用過接口方法

Question

我在兩個片段中實現我的接口我想將數據從活動發送到兩個片段..當我這樣做時，我的數據在第二個片段中發送，而不是在第一個片段中。 它只調用了第二個 Fragment 接口方法..不調用第一個 Fragment 接口方法我不明白請有人幫助....

這是主要活動

     public class MainActivity extends AppCompatActivity implements FragmentCommunication {
     TextView textView;
     ReceiveMessage receiveMessage;
     EditText editText;
     Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.textAcitivity);
        editText = findViewById(R.id.editActivity);
        button = findViewById(R.id.buttonActivity);

        if (findViewById(R.id.fragment1)!= null)
        {
            if (savedInstanceState != null)
            {
                return;
            }
        }

        FirstFragment firstFragment = new FirstFragment();
        SecondFragment secondFragment = new SecondFragment();
        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction()
                .add(R.id.fragment1, firstFragment, null);
        fragmentTransaction.commit();
        FragmentTransaction fragmentTransaction1 = getSupportFragmentManager().beginTransaction().add(R.id.fragment2, secondFragment,null);
        fragmentTransaction1.commit();

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String name = editText.getText().toString().trim();
                 receiveMessage.receiveMessage(name, 3);
            }
        });
    }
    @Override
    public void onAttachFragment(@NonNull Fragment fragment) {
        super.onAttachFragment(fragment);
        try {

            receiveMessage = (ReceiveMessage) fragment;

        } catch (ClassCastException e) {
            throw new ClassCastException(fragment.toString() + " must implement receiveMessage..");
        }

    }
}

這是我的界面

    public interface ReceiveMessage {
    void receiveMessage(String message, int from);
}

這是我的第一個片段

    public class FirstFragment extends Fragment implements ReceiveMessage {
    private View view;
    private TextView textView;
    private EditText editText;
    private Button button;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.firstfragment, container, false);
        textView = view.findViewById(R.id.textView10);
        editText = view.findViewById(R.id.Edit1);
        button = view.findViewById(R.id.button1);
        return view;


    }

    @Override
    public void receiveMessage(String message, int from) {  // THIS METHOD NAVER CALLED WHEN I SEND dATA 
    FROM aCTIVITY
        if (from == 3)
        {
            textView.setText(message);
        }

    }
}

這是我的第二個片段

    public class SecondFragment extends Fragment implements ReceiveMessage {
    private View view;
    private TextView textView;
    private EditText editText;
    private Button button;



    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.secondfragment, container, false);

        textView = view.findViewById(R.id.textView2);
        editText = view.findViewById(R.id.editText2);
        button = view.findViewById(R.id.button);

        return view;
    }




    @Override
    public void receiveMessage(String message, int from) {
        if (from == 3)
        {
            textView.setText(message);
        }
    }
}

Answer 1

每次添加新片段時，都會再次調用活動的“onAttachFragment”。 因此，當您添加第二個片段時，您將“receiveMessage”對象的值重置為第二個片段的接口實現。因此您應該將代碼重寫為：

ReceiveMessage firstReceiver;
ReceiveMessage secondReceiver;

@Override
public void onAttachFragment(Fragment fragment) {
    super.onAttachFragment(fragment);
    if (fragment instanceof FirstFragment) {
       firstReceiver = (ReceiveMessage) fragment;
    } else if (fragment instanceof SecondFragment) {
       secondReceiver = (ReceiverMessage) fragment;
    } 
}



button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            String name = editText.getText().toString().trim();
             firstReceiver.receiveMessage(name, 3);
             secondReceiver.receiveMessage(name, 3); 
        }
});