引入 Butterknife 库导致片段 class 绑定视图时出现运行时异常

Question

我开始重构我的应用程序以使用 Butterknife 库进行视图绑定。在我的 activity class 中，一切都按预期工作，但我无法理解如何在我的静态片段 class 中正确使用 butterknife。我的片段包含一个 RecyclerView 适配器，其中包含一个 CardView 元素列表。

重构前

public static class PlaceholderFragment extends Fragment {

        Activity mActivity;
        RecyclerView mRecyclerView;
        TaskAdapter taskAdapter;
        FloatingActionButton mFabView;
        TextView m_ID;
        TextView mTitle;

...

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {

            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            mRecyclerView = (RecyclerView) rootView.findViewById(R.id.cardList);
            mFabView = (FloatingActionButton) rootView.findViewById(R.id.normal_plus);

            mFabView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

还有

        @Override
        public void onViewCreated(View view, Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
            mRecyclerView.setAdapter(taskAdapter);
            mRecyclerView.setHasFixedSize(true);
            mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
            mRecyclerView.setItemAnimator(new DefaultItemAnimator());
            taskAdapter.SetOnItemClickListener(new TaskAdapter.OnItemClickListener() {

                @Override
                public void onItemClick(View v, int position) {
                    m_ID = (TextView) v.findViewById(R.id._task_id);
                    mTitle = (TextView) v.findViewById(R.id.title);
                    Intent detailIntent = new Intent(v.getContext(), DetailActivity.class);
                    detailIntent.putExtra("TASK_ID", m_ID.getText().toString());
                    detailIntent.putExtra("TASK_TITLE", mTitle.getText().toString());

重构后

public static class PlaceholderFragment extends Fragment {

        Activity mActivity;
        TaskAdapter taskAdapter;
        @Bind(R.id.cardList) RecyclerView mRecyclerView;
        @Bind(R.id.normal_plus) FloatingActionButton mFabView;
        @Bind(R.id._task_id) TextView m_ID;
        @Bind(R.id.title) TextView mTitle;

...

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {

            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            ButterKnife.bind(this, rootView);

...

        @Override
        public void onViewCreated(View view, Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
            mRecyclerView.setAdapter(taskAdapter);
            mRecyclerView.setHasFixedSize(true);
            mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
            mRecyclerView.setItemAnimator(new DefaultItemAnimator());
            taskAdapter.SetOnItemClickListener(new TaskAdapter.OnItemClickListener() {

                @Override
                @OnClick({R.id._task_id, R.id.title})
                public void onItemClick(View v, int position) {
                    ButterKnife.bind(this, v);
                    Intent detailIntent = new Intent(v.getContext(), DetailActivity.class);
                    detailIntent.putExtra("TASK_ID", m_ID.getText().toString());
                    detailIntent.putExtra("TASK_TITLE", mTitle.getText().toString());

我看到的异常是

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.github.idclark.forgetmenot/com.github.idclark.forgetmenot.MainActivity}: java.lang.RuntimeException: Unable to bind views for com.github.idclark.forgetmenot.MainActivity$PlaceholderFragment

...

Caused by: java.lang.RuntimeException: Unable to bind views for com.github.idclark.forgetmenot.MainActivity$PlaceholderFragment
                                                                                    at butterknife.ButterKnife.bind(ButterKnife.java:322)
                                                                                    at butterknife.ButterKnife.bind(ButterKnife.java:279)
                                                                                    at com.github.idclark.forgetmenot.MainActivity$PlaceholderFragment.onCreateView(MainActivity.java:86)

从堆栈跟踪来看，它看起来像那样，因为我现在正在有效地尝试在 onCreateView() 中绑定 m_ID 和 mTitle 而不是 onItemClick() 回调，这就是为什么视图为空。那是对的吗？我还调用了 Butterknife.bind() 两次，一次是在 onCreteView 中调用 mRecyclerView 和 mFabView，但 Butterknife.bind() 也在回调中被调用。如何在适当的时候绑定 m_ID 和 mTitle 视图/除了 onCreateView 我应该使用什么方法？

Answer 1

您应该 ButterKnife.bind(...) 仅一次，在 onCreateView() 中，就像您所做的那样。

对于回调，您应该将 View 转换为实际的自定义 View class（这也绑定了它的小部件！），并获得 title 和 id 从那里：

public class MyCustomView extends FrameLayout {

    public @Bind(R.id._task_id) TextView m_ID;
    public @Bind(R.id.title)  TextView mTitle;

    public MyCustomView(Context context) {
        super(context);
        initialize(context);
    }

    public MyCustomView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initialize(context);
    }

    void initialize(Context context) {
        LayoutInflater.from(context).inflate(R.layout.my_custom_view, this);
        ButterKnife.bind(this);
    }
}

然后你必须

从 PlaceholderFragment
中删除 TextView 的引用
```
  TextView m_ID;
  TextView mTitle;
```

修复处理程序：

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    mRecyclerView.setAdapter(taskAdapter);
    mRecyclerView.setHasFixedSize(true);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    mRecyclerView.setItemAnimator(new DefaultItemAnimator());
    taskAdapter.SetOnItemClickListener(new TaskAdapter.OnItemClickListener() {

        @Override
        @OnClick({R.id._task_id, R.id.title})
        public void onItemClick(View v, int position) {
            MyCustomView myView = (MyCustomView)v;
            Intent detailIntent = new Intent(v.getContext(), DetailActivity.class);
            detailIntent.putExtra("TASK_ID", myView .m_ID.getText().toString());
            detailIntent.putExtra("TASK_TITLE", myView .mTitle.getText().toString());

希望对你有所帮助

引入 Butterknife 库导致片段 class 绑定视图时出现运行时异常

Introducing Butterknife library causes runtime exception in fragment class when binding views

android

android-fragments

refactoring

butterknife