Question

如何在我的ReccylerView适配器中将scrollToPosition(0)添加到addItem()方法中。要更新View，我需要参考Recyclerview？我希望将新的CardView添加到我的RecyclerView列表的顶部，并在插入新卡后让视图显示列表的顶部。请指教。

Adapter.java
...
class ListContactsAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

private class ContactViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

private Context mContext;
private LayoutInflater mLayoutInflater;

private List<Contact> mContacts;
private List<ListItem> mItems;

public ListContactsAdapter(Context context, List<Contact> contacts) {
    mContext = context;
    mLayoutInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    mContacts = contacts;
    mItems = buildItemsList();
}

private List<ListItem> buildItemsList() {
    List<ListItem> items = new ArrayList<>();
       items.add(new ContactItem(contact));            
}

public void addItem(Contact contact) {
    if (mContacts.size()==0) {
        mItems.clear();
        notifyDataSetChanged();
    }

    mContacts.add(contact);
    mItems.add(new ContactItem(contact));
    notifyItemInserted(0);
}

以下是添加项目的活动代码：

...
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Contact contact = new Contact("", "");
            mContactsAdapter.addItem(contact);
            // need to figure out scrollToPosition(0) here
        }
    });

如果我使用recyclerView.scrollToPosition（0）; Android Studio报告以下错误：＆＃34;变量＆＃39; recyclerView＆＃39;从内部类中访问，需要被声明为final。＆＃34;

Answer 1

RecyclerView有两种方法scrollToPosition和smoothScrollToPosition，您可以使用这些方法在notifyItemInserted()

之后显示列表的顶部

将recyclelerview声明为Activity的成员变量，而不是方法中的局部变量，就像mContactsAdapter一样。

示例代码：

public class XXXActivity extends Activity{
    RecyclerView mRecyclerView;
    // ....

    public void initViews(){
        mRecyclerView = (RecyclerView) findViewById(R.id.xxx);
        // ....
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Contact contact = new Contact("", "");
                mContactsAdapter.addItem(contact);
                mRecyclerView.scrollToPosition(0);
            }
        });
    }
    // ....
}

Android RecyclerView：如何将scrollToPosition（0）添加到Adapter？

1 个答案: