一个关于多选框列表的问题，求大神帮忙

每次app运行到显示多选框的时候及报空指针错误，我想是不是这个数组的问题

 final String[] group_device = new String[64];
        for(i = 0; i < Sysparam.all_device.size(); i++)
        {
            group_device[i] = Sysparam.all_device.get(i).getName();
        }

        //group_device.
                //System.out.println(group_device[0]);
        builder.setView(editText);
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener()
        {
            @Override
            public void onClick(DialogInterface dialog, int which)
            {
                Sysparam.group_name[Sysparam.i] = G_name;
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setTitle("选择设备加入分组");
                builder.setMultiChoiceItems(group_device, checkedItems, new DialogInterface.OnMultiChoiceClickListener() {
                            public void onClick(DialogInterface dialog, int whichButton,
                                                boolean isChecked) {
                                if(isChecked) {
                                    Sysparam.all_device.get(whichButton).set_group((0x0001<<Sysparam.i)|Sysparam.all_device.get(whichButton).get_group());
                                }else {
                                    Sysparam.all_device.get(whichButton).set_group((0xfffe<<Sysparam.i)&Sysparam.all_device.get(whichButton).get_group());
                                }
                            }
                        });

需要错误日志，请先贴错误日志