从适配器单击事件到 Android 中的 Activity 或 Fragment

Question

我已经自定义了在导航抽屉中显示的可扩展列表视图。我在适配器中有一个点击监听器我想将点击事件从适配器发送到我的活动或片段。

如果可以，我该怎么做？

这是我的适配器的 sn-p：

公共类 CustomAdapter 实现 ExpandableListAdapter {

    @Override
    public View getGroupView(int position, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.menu_item, parent, false);
        }

        TextView text = (TextView) convertView.findViewById(android.R.id.text1);
        text.setText(items.get(position).getName());
        ImageView imageView = (ImageView) convertView.findViewById(R.id.imageIndicator);

        if (items.get(position).isHasChild() && items.get(position).getSubMenuItems().size() > 0)
            imageView.setVisibility(View.VISIBLE);
        else
            imageView.setVisibility(View.INVISIBLE);

        if (isExpanded)
            imageView.setImageResource(R.drawable.down);
        else
            imageView.setImageResource(R.drawable.next);

        return convertView;
    }

    @Override
    public View getChildView(final int childPosition, int groupPosition, boolean isExpanded, View convertView, final ViewGroup parent) {

        View view = convertView;

        if (view == null) {
            view = inflater.inflate(R.layout.expandable_list, parent, false);
        }
        ExpandableHeightListView childList = (ExpandableHeightListView) view.findViewById(R.id.childList);
        childList.setAdapter(new CustomAdapter(context, items.get(childPosition).getSubMenuItems()));
        childList.invalidate();
        parent.invalidate();

        final ExpandableHeightListView list = childList;
        childList.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            int previousItem = -1;

            @Override
            public void onGroupExpand(int groupPosition) {
                ArrayList<eMenuItem> tempItems = items.get(childPosition).getSubMenuItems();

                if (tempItems.get(groupPosition).getSubMenuItems().size() == 0) {
                    Toast.makeText(context, "Start Activity", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(context, "Clicked on " + tempItems.get(groupPosition).getName(), Toast.LENGTH_SHORT).show();
                }

                if (groupPosition != previousItem)
                    list.collapseGroup(previousItem);

                previousItem = groupPosition;
                list.invalidate();
                parent.invalidate();
            }
        });
        return view;
    }
}

在 Jared Burrows 的帮助下 - How to create interface between Fragment and adapter?

在我的 CustomAdapter 和 FragmentActivity 中添加了一些东西

public class CustomAdapter implements ExpandableListAdapter {

public CustomAdapter(MainActivity fragmentactivity) 
{
    try 
    {
        this.mAdapterCallback = ((AdapterCallback) fragmentactivity);
    } 
    catch (ClassCastException e) 
    {
        throw new ClassCastException("Fragment must implement AdapterCallback.");
    }
}

public static interface AdapterCallback 
{
    void onMethodCallback();
}

    @Override
    public View getGroupView(int position, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.menu_item, parent, false);
        }

        TextView text = (TextView) convertView.findViewById(android.R.id.text1);
        text.setText(items.get(position).getName());
        ImageView imageView = (ImageView) convertView.findViewById(R.id.imageIndicator);

        if (items.get(position).isHasChild() && items.get(position).getSubMenuItems().size() > 0)
            imageView.setVisibility(View.VISIBLE);
        else
            imageView.setVisibility(View.INVISIBLE);

        if (isExpanded)
            imageView.setImageResource(R.drawable.down);
        else
            imageView.setImageResource(R.drawable.next);

        return convertView;
    }

    @Override
    public View getChildView(final int childPosition, int groupPosition, boolean isExpanded, View convertView, final ViewGroup parent) {

        View view = convertView;

        if (view == null) {
            view = inflater.inflate(R.layout.expandable_list, parent, false);
        }
        ExpandableHeightListView childList = (ExpandableHeightListView) view.findViewById(R.id.childList);
        childList.setAdapter(new CustomAdapter(context, items.get(childPosition).getSubMenuItems()));
        childList.invalidate();
        parent.invalidate();

        final ExpandableHeightListView list = childList;
        childList.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            int previousItem = -1;

            @Override
            public void onGroupExpand(int groupPosition) {
                ArrayList<eMenuItem> tempItems = items.get(childPosition).getSubMenuItems();

                if (tempItems.get(groupPosition).getSubMenuItems().size() == 0) {
                    Log.e("value","position"+childPosition);
                Log.e("value","position"+groupPosition);
                Log.e("value","position"+tempItems.get(groupPosition).getName());

                mAdapterCallback.onMethodCallback();

                } else {
                    Toast.makeText(context, "Clicked on " + tempItems.get(groupPosition).getName(), Toast.LENGTH_SHORT).show();
                }

                if (groupPosition != previousItem)
                    list.collapseGroup(previousItem);

                previousItem = groupPosition;
                list.invalidate();
                parent.invalidate();
            }
        });
        return view;
    }
}

在我的主要活动中：

public class MainActivity extends FragmentActivity implements AdapterCallback
{
 @Override
  protected void onCreate(Bundle savedInstanceState)
  {
    this.mMyAdapter = new CustomAdapter(this);
   }

然后在 Oncreate 之外添加这个：

public void onMethodCallback() 
{
        Log.e("Call","VALUE");
 }
 }

但我仍然收到 NPE 错误。这很奇怪，当我不使用回调时，我没有得到 NPE，但是当我使用回调时，我得到 NPE：http://pastebin.com/wc2ByiFz

Answer 1

   public class CustomAdapter implements ExpandableListAdapter {

    Activity yourActivity
     public CustomAdapter(Activity yourActivity)
                    {

            this.yourActivity= yourActivity;

                }

    @Override
    public View getGroupView(int position, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.menu_item, parent, false);
        }

        TextView text = (TextView) convertView.findViewById(android.R.id.text1);
        text.setText(items.get(position).getName());
        ImageView imageView = (ImageView) convertView.findViewById(R.id.imageIndicator);

        if (items.get(position).isHasChild() && items.get(position).getSubMenuItems().size() > 0)
            imageView.setVisibility(View.VISIBLE);
        else
            imageView.setVisibility(View.INVISIBLE);

        if (isExpanded)
            imageView.setImageResource(R.drawable.down);
        else
            imageView.setImageResource(R.drawable.next);

        return convertView;
    }

    @Override
    public View getChildView(final int childPosition, int groupPosition, boolean isExpanded, View convertView, final ViewGroup parent) {

        View view = convertView;

        if (view == null) {
            view = inflater.inflate(R.layout.expandable_list, parent, false);
        }
        ExpandableHeightListView childList = (ExpandableHeightListView) view.findViewById(R.id.childList);
        childList.setAdapter(new CustomAdapter(context, items.get(childPosition).getSubMenuItems()));
        childList.invalidate();
        parent.invalidate();

        final ExpandableHeightListView list = childList;
        childList.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            int previousItem = -1;

            @Override
            public void onGroupExpand(int groupPosition) {
                ArrayList<eMenuItem> tempItems = items.get(childPosition).getSubMenuItems();

                if (tempItems.get(groupPosition).getSubMenuItems().size() == 0) {
                     yourActivity.onYourClick(groupPosition);
                } else {
                    Toast.makeText(context, "Clicked on " + tempItems.get(groupPosition).getName(), Toast.LENGTH_SHORT).show();
                }

                if (groupPosition != previousItem)
                    list.collapseGroup(previousItem);

                previousItem = groupPosition;
                list.invalidate();
                parent.invalidate();
            }
        });
        return view;
    }
}

//Your Fragment

    public class yourActivity extends FragmentActivity{
            public void onYourClick(int groupPosition){
            }