AlertDialog android studio

我试图显示一个包含加载动画的alert 对话框.单击最初显示的另一个alert 对话框后，需要显示alert 对话框.基本上，第一个对话框包含一个setPositive和setNegative按钮.setPositive事件会触发一个需要几秒钟的过程.我希望在加载过程开始时出现包含加载动画的第二个对话框.在加载对话框显示完成之前，我无法关闭第一个对话框.

//dialog that contains loading animation
    public class LoadingBox {
    Activity myActivity;
    AlertDialog dialog;

    LoadingBox(Activity activity){
        myActivity = activity;
    }
     void startLoadingDialog(){
        AlertDialog.Builder builder = new AlertDialog.Builder(myActivity);
        LayoutInflater inflater = myActivity.getLayoutInflater();
        builder.setView(inflater.inflate(R.layout.layout_dialog,null));
        builder.setCancelable(true);
        dialog = builder.create();
        dialog.show();
    }
    void dismissDialog(){
        dialog.dismiss();
    }
}

 

      
     new AlertDialog.Builder(SmsListActivity.this)
    
                            .setIcon(android.R.drawable.ic_dialog_alert)
                            .setTitle("Add To Transaction List")
                            .setMessage("Please note that this process might take long. Proceed?")
                            .setPositiveButton("yes", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    LoadingBox loadingBox = new LoadingBox(SmsListActivity.this);
    
                                    loadingBox.startLoadingDialog();
    
                                    addPendingToList();
                                    loadingBox.dismissDialog();
    
    
                                }
                            }).setNegativeButton("No",null).show();