比较存储在数据库中的日期并计算天数

Question

我有一个以String格式存储日期的数据库。我正在访问数据库并在列表视图中显示它。现在，我想要的是我想比较相邻的日期来计算它们之间的天数，并将它们显示为同一屏幕中的列表。 这是我的代码：

MainActivity：

public class LogActivity extends Activity {
SqlHandler sqlHandler;
 ListView lv;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_log);

    lv = (ListView) findViewById(R.id.lv_custom_list);
    sqlHandler = new SqlHandler(this);
     showList();
}
private void showList() {

      ArrayList<PredictedDateItems> predicteddateList = new ArrayList<PredictedDateItems>();
      predicteddateList.clear();
      String query = "SELECT * FROM predicted_date_record_table ORDER BY _id DESC ";
      Cursor c1 = sqlHandler.selectQuery(query);
      //if(c1==null)
     // {
        //   TextviewMsz = (TextView)findViewById(R.id.logview);
     // }

      if (c1 != null)  {
       if (c1.moveToFirst()) {
        do {
            PredictedDateItems predictedDateItems = new PredictedDateItems();

            predictedDateItems.setSlno(c1.getString(c1
           .getColumnIndex("_id")));
            predictedDateItems.setDate(c1.getString(c1
           .getColumnIndex("predicted_date")));


         predicteddateList.add(predictedDateItems);




        } while (c1.moveToNext());
       }
      }

      c1.close();



      PredictedDateAdapter predicteddateListAdapter = new PredictedDateAdapter(
              LogActivity.this, predicteddateList);
      lv.setAdapter(predicteddateListAdapter);

} }

适配器类： 公共类PredictedDateAdapter扩展了BaseAdapter {

Context context;
ArrayList<PredictedDateItems> predicteddateList;

public PredictedDateAdapter(Context context, ArrayList<PredictedDateItems> list) {

    this.context = context;
    predicteddateList = list;
}

@Override
public int getCount() {
    return predicteddateList.size();

}

@Override
public Object getItem(int position) {
     return predicteddateList.get(position);
}

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

@Override
public View getView(int position, View convertView, ViewGroup arg2) {
    PredictedDateItems predictedDateItems = predicteddateList.get(position);

    if (convertView == null) {
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.date_list_row, null);

    }
   // TextView tvSlNo = (TextView) convertView.findViewById(R.id.tv_slno);
    //tvSlNo.setText(contactListItems.getSlno());
    TextView tvDate = (TextView) `.findViewById(R.id.tv_predicted_date);
    tvDate.setText(predictedDateItems.getDate());


    return convertView;
}

}