Question

我不知道在旋转列表时是否有任何错误或需要做其他事情。如果有人能帮助我找出解决方案，我会非常感激。

我有一个垂直ListView，有5个项目（在屏幕截图的左侧），如屏幕截图所示：

正如您所看到的，每次单击或选择项目时都应该旋转列表。问题是我实现的代码与onItemClickListener一起使用（当单击的项目位于项目下方或上方的一个位置时中间），但它不适用onItemSelectedListener（列表旋转两次（单向），然后停止向该方向旋转，这意味着onItemSelected根本不被调用。

可能会有更多屏幕截图显示：

好吧，这可能会让你更加困惑..我想要一个列表，其中所选项目采用中间（文本颜色蓝色）位置，列表相应地旋转。请帮助....非常感谢。

源代码：主要活动：

public class MainActivity extends AppCompatActivity {



      private ListView categoryList;
    ListCustomAdapter listadapter;
      private List<TextItem> txtItems;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
     categoryList = (ListView) findViewById(R.id.listCategories);
     listadapter=new ListCustomAdapter(this,txtItems);
            categoryList.setAdapter(listadapter);
    categoryList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {

                    listadapter.getPosition(i);
                    Log.d("position",""+i);
                    if(i>2) {
                        Log.d("position1",""+(i-1));
                        Collections.rotate(txtItems, 4);
                        listadapter.notifyDataSetChanged();
                    }else if(i<2){
                        Log.d("position2",""+(1-i));
                        Collections.rotate( txtItems,1);
                        listadapter.notifyDataSetChanged();
                    }
                    else{

                    }

                }
            });



            categoryList.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {

                    Log.e("inside" ,"onItemSelected");
                    if(i>2) {

                        Collections.rotate(txtItems,4);
                        Log.d("position rotated",""+i);
                        listadapter.notifyDataSetChanged();

                    }else if(i<2){
                        Collections.rotate( txtItems,1);
                        listadapter.notifyDataSetChanged();
                    }



                }

                @Override
                public void onNothingSelected(AdapterView<?> adapterView) {
                Log.e("inside" ,"onNothingSelected");
                }
            });
    }

ListCustomAdapter：

   public class ListCustomAdapter extends BaseAdapter {


        private Activity activity;
        private LayoutInflater inflater;
        private List<TextItem> txtItems;
        int pos;

        public ListCustomAdapter(Activity activity, List<TextItem> txtItems) {
            this.activity = activity;
            this.txtItems = txtItems;
        }



        @Override
        public int getCount() {
            return txtItems.size();
        }

        @Override
        public Object getItem(int location) {
            return txtItems.get(location);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        /*
        inflate the items in the list view
         */
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder = null;


            if (inflater == null) {
                inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            }
            if (convertView == null) {
                convertView = inflater.inflate(R.layout.vertical_list_item, null);
                holder = new ViewHolder();
                holder.category = (TextView) convertView.findViewById(R.id.category_name);
                holder.listLayout= (LinearLayout) convertView.findViewById(R.id.list_layout);
                convertView.setTag(holder);
            }else
            {
                holder = (ViewHolder) convertView.getTag();
            }

            if (pos == position) {
                Log.d("translated","done of position"+pos);
                holder.category.setTranslationX(10.17f);

            } else {
              /*  view.imgViewFlag.getLayoutParams().height = 140;
                view.imgViewFlag.getLayoutParams().width = 300;*/
                holder.category.setTranslationX(1.0f);
                Log.d("translated","default of position"+pos);
                // view.imgViewFlag.setBackgroundResource(0);
                holder.category.setBackgroundResource(0);

            }
            TextItem model = txtItems.get(position);
            holder.category.setText(model.getTitleName());

            if(position==2)
                holder.category.setTextColor(Color.BLUE);




        /*
        creating objects to access the views
         */

            return convertView;
        }
        public void getPosition(int position) {
            this.pos = position;
        }
        static class ViewHolder {
            TextView category;
            LinearLayout listLayout;

        }
    }

Answer 1

由于我的代码适用于OnItemClickListener，我发现点击的项目在列表中设置为选中..对于OnItemSelectedListener ...我必须始终将中间位置设置为选中..因此，我添加了以下

categoryList.setSelection(2); /*2 is the mid position for the list with 5 items *\

列表旋转后

，即：

categoryList.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {

                Log.e("inside" ,"onItemSelected");
                if(i>2) {

                    Collections.rotate(txtItems,4);
                    categoryList.setSelection(2);
                    Log.d("position rotated",""+i);
                    listadapter.notifyDataSetChanged();

                }else if(i<2){
                    Collections.rotate( txtItems,1);
                    categoryList.setSelection(2);
                    listadapter.notifyDataSetChanged();
                }



            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {
            Log.e("inside" ,"onNothingSelected");
            }
        });

如何旋转列表使得从列表中选择的项始终位于列表视图中的中间位置

1 个答案: