按下后退按钮时，应用始终崩溃

Question

我正在使用应用ListView显示一些数据的应用程序。一切正常，但是当我按下“后退”按钮时，我的应用程序崩溃了，我得到NullPointer Exception。这是我的基本适配器：

private Context context;
private Industry industries;

public IndustryAdapter(Context context, Industry industries) {
    this.industries = industries;
    this.context = context;
}

@Override
public int getCount() {
    return 1;
}

@Override
public Object getItem(int position) {
    return 1;
}

@Override
public long getItemId(int position) {
    return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if (convertView == null) {
        LayoutInflater inflater = ((Activity) context).getLayoutInflater();

        convertView = inflater.inflate(R.layout.row_item, parent, false);
    }

    TextView tvName = (TextView)convertView.findViewById(R.id.tvName);
    TextView tvDescription = (TextView)convertView.findViewById(R.id.tvDescription);

    String name = industries.getName();
    String descr = industries.getDescription();

    tvName.setText(name);
    tvDescription.setText(descr);

    return convertView;
}

private Context getContext() {
    return context;
}

问题在于此行： 字符串名称= industries.getName（）; 字符串descr = industries.getDescription（）;

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String al.sqmo.model.Industry.getName()' on a null object reference