使用ArrayAdapters时，单击按钮将ListView选项模式从singleChoice更改为MultipleEchoiceMode

Question

事实上，我想实现一些类似于我们手机中常见的聊天/MSG删除功能。单击菜单上的删除按钮时，行选择复选框必须出现，顶部的标签显示所选行数。选择行数后点击右上角的“完成/删除”按钮时，必须出现删除确认对话框，并且必须删除所选行。我在下图中突出显示了所需的功能。[图像1-菜单中的按钮][1][图像2-单击删除按钮时的多模式外观][2][图像3-选择和标签][3][图像4-确认对话框][4]。这是我到目前为止编写的代码，但我的代码不起作用，需要帮助。这是我的密码：

//for the start I want the list be in single mode

        ListView listView = (ListView) findViewById(R.id.listView);
        ArrayAdapter arrList = new ArrayAdapter<String>(this, 
        安卓.R.layout.simple_list_item_single_choice, namesList);
        listView.setAdapter(arrList);

 // for the list to be in multimode on clicking the button in the menu

        public boolean onCreateOptionsMenu(Menu menu) 
        {
        getMenuInflater().inflate(R.menu.mymenu, menu);
        return true;
        }  
        @Override
        public boolean onOptionsItemSelected(MenuItem item) {

        int id = item.getItemId();


        if (id == R.id.deletebutton) {
        if (namesList.size() != 0) {
                if (mListView.getChoiceMode() == ListView.CHOICE_MODE_SINGLE) {
                    mListView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
                    directoryList = new ArrayAdapter<String>(this,
                            安卓.R.layout.simple_list_item_multiple_choice, 
                    namesList);
                    delete();
                }


            } else {
                Toast.makeText(getApplicationContext(), "names not found", 
                      Toast.LENGTH_SHORT).show();
            }

        }

        return super.onOptionsItemSelected(item);
    }
// delete method implementation
        AlertDialog.Builder a_builder = new AlertDialog.Builder(this);
                a_builder.setTitle("Confirm Delete?");
                a_builder.setMessage("DELETE")
                        .setCancelable(true)
                        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                int i;
                                SparseBooleanArray checkedItemPositions = mListView.getCheckedItemPositions();
                                int itemCount = listView.getCount();
                                for (i = itemCount - 1; i >= 0; i--) {
                                    if (checkedItemPositions.get(i)) {
                                        arrList.remove(namesList.get(i));
                                    }
                                }
                                checkedItemPositions.clear();
                                arrList.notifyDataSetChanged();

                                    Toast.makeText(getApplicationContext(), "Deleted", Toast.LENGTH_SHORT).show();
                                   .setNegativeButton("No", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.cancel();
                            }
                        });





  [1]: https://i.stack.imgur.com/ZR1Wv.png
  [2]: https://i.stack.imgur.com/4gJGd.png
  [3]: https://i.stack.imgur.com/uvn9p.png
  [4]: https://i.stack.imgur.com/3gsML.png