AlertDialog MultipleChoice不显示项目

我在显示项目int AlertDialog时遇到问题。我检查了代码，没关系。只有items不显示。AlertDialog MultipleChoice不显示项目

这里是我的代码：

//PREFERENCE CATEGORY - DIALOG 
public void alertDialogPrefCat(){ 
    //TODO - 
    String[] categories = new String[]{"Health","Universities","Scholars","Professionals", 
          "Business","Engineering","Architecture","Foundations", 
          "Charities", "Culture", "Technology","Blog", "Music", 
          "Sports","Insurance"}; 
    //GET CHECKED 
     final boolean[] selectedCategory = new boolean[]{false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false, 
              false 
     }; 

    AlertDialog.Builder alertDialogCategoryPicker = new AlertDialog.Builder(this); 
    final List<String> itemGet = Arrays.asList(categories); 

    alertDialogCategoryPicker.setTitle("Interest: ") 
          .setMessage("Select category of org you want.") 
          .setCancelable(false) 
          .setMultiChoiceItems(categories, selectedCategory, 
          new DialogInterface.OnMultiChoiceClickListener() { 
          @Override 
          public void onClick(DialogInterface dialog, int which, boolean isChecked) { 
           selectedCategory[which] = isChecked; 
           String currentItem = itemGet.get(which); 
           Toast.makeText(MainActivity.this, currentItem, Toast.LENGTH_SHORT).show(); 
           } 
          }) 
          .setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() { 
            @Override 
            public void onClick(DialogInterface dialog, int which) { 

            } 
          }); 

    AlertDialog dialogCategory = alertDialogCategoryPicker.create(); 
    dialogCategory.show(); 

}

我得到这个对话空项。