Fragment中的AndroidStudioButtononClick監聽器

我是新手，我試圖學習導航抽屜。我想在 Fragment 中的一個按鈕上設定一個 onClick 偵聽器，但是當我運行應用程式時，該按鈕什么也不做。

這是WeightFragment.java：`

public class WeightFragment extends Fragment {

    private FragmentWeightBinding binding;
    private EditText edtNumber;
    private Button addBtn;

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
        WeightViewModel weightViewModel =
                new ViewModelProvider(this).get(WeightViewModel.class);

        binding = FragmentWeightBinding.inflate(inflater, container, false);
        View root = binding.getRoot();

        View view = inflater.inflate(R.layout.fragment_weight, container, false);
        addBtn = view.findViewById(R.id.addBtn);
        edtNumber = view.findViewById(R.id.edtNumber);
        String weight = String.valueOf(edtNumber.getText());
        SimpleDateFormat sdf = new SimpleDateFormat("'Date\n'dd-MM-yyyy HH:mm:ss");
        String currentDateAndTime = sdf.format(new Date());

        addBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(getActivity(),weight   currentDateAndTime, Toast.LENGTH_SHORT).show();
            }
        });

        final TextView textView = binding.txtDate;
        weightViewModel.getText().observe(getViewLifecycleOwner(), textView::setText);
        return root;
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        binding = null;
    }
}

我試過：

public class WeightFragment extends Fragment implements View.OnClickListener

并實作該方法，但無論如何它都不起作用。

uj5u.com熱心網友回復：

這是因為您在onClickListener丟棄的視圖上設定了。

這是系結（請注意root）：

binding = FragmentWeightBinding.inflate(inflater, container, false);
View root = binding.getRoot();

但是您正在將偵聽器設定在以下按鈕上：

View view = inflater.inflate(R.layout.fragment_weight, container, false);
addBtn = view.findViewById(R.id.addBtn);
addBtn.setOnClickListener(...);

最后你return root;

具有 onClick 偵聽器的視圖在那里，您創建了它，但最終它被丟棄了。

只需替換view它就binding可以了。

public View onCreateView(
    @NonNull LayoutInflater inflater,
    ViewGroup container, 
    Bundle savedInstanceState
) {
    WeightViewModel weightViewModel = new ViewModelProvider(this).get(WeightViewModel.class);

    binding = FragmentWeightBinding.inflate(inflater, container, false);
    View root = binding.getRoot();
    addBtn = binding.addBtn;
    edtNumber = binding.edtNumber;
    String weight = String.valueOf(edtNumber.getText());
    SimpleDateFormat sdf = new SimpleDateFormat("'Date\n'dd-MM-yyyy HH:mm:ss");
    String currentDateAndTime = sdf.format(new Date());

    addBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Toast.makeText(getActivity(),weight   currentDateAndTime, Toast.LENGTH_SHORT).show();
        }
    });

    final TextView textView = binding.txtDate;
    weightViewModel.getText().observe(getViewLifecycleOwner(), textView::setText);
    return root;
}

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