Android 如何在单击 RecyclerView 项目时从 fragment 发送 Intent

Question

我的应用使用 fragment 中包含的 RecyclerView 进行编码。我能够使用模拟数据列表成功填充 RecyclerView，但是我不知道如何在单击其中一个项目时将 Intent 发送到另一个 Activity。当我尝试从 fragment 中调用 StartActivity 时，Android Studio 无法解析该方法。

我的 onItemClick 是通过我的 viewholder 类中的接口(interface)实现的。该接口(interface)还会生成错误 inner classes cannot have static declarations。我想知道我是否无法从 fragment 中调用 StartActivity，因为我的 RecyclerView 适配器或 viewholder 类都没有扩展 Activity。

单击 RecyclerView 中的项目时发送 Intent 的适当实现是什么？

占位符 fragment

public static class PlaceholderFragment extends Fragment {

        Activity mActivity;
        RecyclerView mRecyclerView;
        TaskAdapter taskAdapter;

        public PlaceholderFragment() {
        }

        @Override
        public void onAttach(Activity activity) {
            super.onAttach(activity);
            this.mActivity = (Activity) activity;
            setRetainInstance(true);
        }

        @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);
            taskAdapter = new TaskAdapter(createList(30));
            return 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());

            //Cannot resolve method 
            taskAdapter.SetItemClickListener(new TaskAdapter.TaskViewHolder.OnItemClickListener() {

                @Override
                public void onItemClick(View v, int position) {
                    Intent detailIntent = new Intent(v.getContext(), DetailActivity.class);
                    //Cannot resolve method 
                    StartActivity(detailIntent);

                }
            });

        }

        private List<Task> createList(int size) {
            List<Task> result = new ArrayList<>();
            for (int i = 1; i<=size; i++) {
                Task task = new Task();
                task.title = Task.TITLE_PREFIX + i;
                task.updated = Task.UPDATED_PREFIX +i;
                task.notes = task.NOTES_PREFIX + i;

                result.add(task);

            }
            return result;
        }
    }

任务适配器

public class TaskAdapter extends RecyclerView.Adapter<TaskAdapter.TaskViewHolder> {

    private List<Task> taskList;
    TaskViewHolder.OnItemClickListener mItemClickListener;

    public TaskAdapter(List<Task> taskList) {
        this.taskList = taskList;
    }

    @Override
    public int getItemCount() {
        return taskList.size();
    }

    @Override
    public void onBindViewHolder(TaskViewHolder taskViewHolder, int i) {
        Task task = taskList.get(i);
        taskViewHolder.mTitle.setText(task.title);
        taskViewHolder.mUpdated.setText(task.updated);
        taskViewHolder.mStatus.setChecked(false);
    }

    @Override
    public TaskViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {

        View itemView = LayoutInflater.from(viewGroup.getContext()).
                inflate(R.layout.tasklist_layout, viewGroup, false);

        return new TaskViewHolder(itemView);
    }

    public class TaskViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        protected TextView mTitle;
        protected TextView mUpdated;
        protected CheckBox mStatus;

        public TaskViewHolder(View view) {
            super(view);
            mTitle = (TextView) view.findViewById(R.id.title);
            mUpdated = (TextView) view.findViewById(R.id.updated);
            mStatus = (CheckBox) view.findViewById(R.id.status);
            view.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            if (mItemClickListener != null) {
                mItemClickListener.onItemClick(v, getPosition());
            }
        }
        //Inner Classes cannot have static declarations
        public interface OnItemClickListener {
            void onItemClick(View view , int position);
        }

        public void SetOnItemClickListener(final OnItemClickListener mItemClickListener) {
            //cannot resolve symbol 
            this.mItemClickListener = mItemClickListener;
        }
    }
}

Answer 1

startActivity() 方法以小 s 开头。试试下面的代码行

   //Cannot resolve method 
        taskAdapter.TaskViewHolder.SetItemClickListener(new TaskAdapter.TaskViewHolder.OnItemClickListener() {

            @Override
            public void onItemClick(View v, int position) {
                Intent detailIntent = new Intent(v.getContext(), DetailActivity.class);
                //Cannot resolve method 
                getActivity().startActivity(detailIntent);

            }
        });

SetOnItemClickListener() 应该在 TaskViewHolder 类之外。试试下面的方法，看看是否有帮助。

public class TaskAdapter extends RecyclerView.Adapter<TaskAdapter.TaskViewHolder> {

private List<Task> taskList;
TaskViewHolder.OnItemClickListener mItemClickListener;

public TaskAdapter(List<Task> taskList) {
    this.taskList = taskList;
}

@Override
public int getItemCount() {
    return taskList.size();
}

@Override
public void onBindViewHolder(TaskViewHolder taskViewHolder, int i) {
    Task task = taskList.get(i);
    taskViewHolder.mTitle.setText(task.title);
    taskViewHolder.mUpdated.setText(task.updated);
    taskViewHolder.mStatus.setChecked(false);
}

@Override
public TaskViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {

    View itemView = LayoutInflater.from(viewGroup.getContext()).
            inflate(R.layout.tasklist_layout, viewGroup, false);

    return new TaskViewHolder(itemView);
}

public class TaskViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    protected TextView mTitle;
    protected TextView mUpdated;
    protected CheckBox mStatus;

    public TaskViewHolder(View view) {
        super(view);
        mTitle = (TextView) view.findViewById(R.id.title);
        mUpdated = (TextView) view.findViewById(R.id.updated);
        mStatus = (CheckBox) view.findViewById(R.id.status);
        view.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        if (mItemClickListener != null) {
            mItemClickListener.onItemClick(v, getPosition());
        }
    }
    //Inner Classes cannot have static declarations
    public interface OnItemClickListener {
        void onItemClick(View view , int position);
    }
}

 public void SetOnItemClickListener(final OnItemClickListener mItemClickListener) {
        //cannot resolve symbol 
        this.mItemClickListener = mItemClickListener;
    }
}