Android convert numbers into date format

Question

I am storing month and year in my android database. I want to fetch it and convert it to date format so that I can match it with current month and year present in array. Im fetching it through ArrayList but how to convert in date format and match?

private ArrayList<String> getGspApprovedMonthData() {
    List<Date> dates = new ArrayList<>(gspApprovedMonth.size());
    gspApprovedMonth.clear();
    SqlDataStore sd = new SqlDataStore(this);
    sd.open();
    String gspQuery = " SELECT * FROM "+ TABLE_GSP_APPROVED_DATA;
    Cursor gspCu = sd.getData(gspQuery);
    if(gspCu.moveToFirst()){
        do {
            String gspMonth = gspCu.getString(gspCu.getColumnIndex(Queryclass.GSP_APPROVED_MONTH));
            String gspYr = gspCu.getString(gspCu.getColumnIndex(Queryclass.GSP_APPROVED_YEAR));

            gspApprovedMonth.add(gspMonth+gspYr);
        } while (gspCu.moveToNext());
    }
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    for (String dateString : gspApprovedMonth) {
        try {
            dates.add(sdf.parse(dateString));
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }
    gspCu.close();
    sd.close();
    return gspApprovedMonth;
}

Answer 1

java.time

The java.util date-time API and their formatting API, SimpleDateFormat were supplanted by the modern date-time API in Mar 2014. Since then, it is highly recommended to stop using the legacy date-time API.

Solution using java.time, the modern date-time API:

The java.time API provides you with Year that you can combine with a month using Year#atMonth to get a YearMonth. A YearMonth can be compared with another using its methods like YearMonth#isAfter, YearMonth#isBefore etc.

Demo:

import java.time.Year;
import java.time.YearMonth;

class Main {
    public static void main(String[] args) {
        // Sample year and month strings
        String strYear = "2022";
        String strMonth = "9";
        YearMonth ym = Year.of(Integer.parseInt(strYear))
                           .atMonth(Integer.parseInt(strMonth));
        System.out.println(ym);

        // Comparing two instances of YearMonth
        YearMonth currentYm = YearMonth.now();
        if (ym.isAfter(currentYm))
            System.out.println(ym + " is after " + currentYm);
        else
            System.out.println(ym + " is before or equal to " + currentYm);
    }
}

Output:

2022-09
2022-09 is before or equal to 2023-01

ONLINE DEMO

How to implement it in your code?

List<YearMonth> yearMonths = new ArrayList<>(gspApprovedMonth.size());

// ...

if(gspCu.moveToFirst()){
    do {
        String gspMonth = gspCu.getString(gspCu.getColumnIndex(Queryclass.GSP_APPROVED_MONTH));
        String gspYr = gspCu.getString(gspCu.getColumnIndex(Queryclass.GSP_APPROVED_YEAR));

        yearMonths.add(Year.of(Integer.parseInt(gspYr))
                           .atMonth(Integer.parseInt(gspMonth)));
        // ...
    } while (gspCu.moveToNext());
}
// ...

Learn more about the modern Date-Time API from Trail: Date Time.