{"id":12462,"date":"2022-09-30T20:22:49","date_gmt":"2022-09-30T14:52:49","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-how-can-i-add-one-month-to-change-into-the-milliseconds\/"},"modified":"2022-09-30T20:22:49","modified_gmt":"2022-09-30T14:52:49","slug":"solved-how-can-i-add-one-month-to-change-into-the-milliseconds","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-how-can-i-add-one-month-to-change-into-the-milliseconds\/","title":{"rendered":"[Solved] How can I add one month to change into the milliseconds?"},"content":{"rendered":"

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I suggest: First, instead of your variables (fields?) year<\/code>, month<\/code>, day<\/code>, hours<\/code> and minutes<\/code> just declare<\/p>\n

private LocalDate date;\nprivate LocalTime time;\nprivate long milliseconds;\n<\/code><\/pre>\n
(Keep the milliseconds<\/code> variable since you will want to have your result here.)<\/p>\n
In onDateSet<\/code> assign a value to date<\/code> in this way:<\/p>\n
        date = LocalDate.of(selectedYear, selectedMonth + 1, selectedDate);\n<\/code><\/pre>\n
This is where we are taking into account, as you said, that the date picker\u2019s selectedMonth<\/code> is 0-based, while LocalDate<\/code> numbers months the way humans do, from 1.<\/p>\n
Now your timePicker<\/code> method becomes<\/p>\n
private void timePicker(){\n    \/\/ Get Current Time\n    time = LocalTime.now(ZoneId.systemDefault());\n    \/\/ Launch Time Picker Dialog\n    TimePickerDialog timePickerDialog = new TimePickerDialog(this,\n            android.R.style.Theme_Holo_Light_Dialog,\n            new TimePickerDialog.OnTimeSetListener() {\n\n                @Override\n                public void onTimeSet(TimePicker view, int hourOfDay,int minute) {\n\n                    time = LocalTime.of(hourOfDay, minute);\n\n                    milliseconds = date.atTime(time)\n                            .atZone(ZoneId.systemDefault())\n                            .toInstant()\n                            .toEpochMilli();\n                    Log.e(\"LONGGGGGGG\", String.valueOf(milliseconds));\n                }\n            },\n            time.getHour(),\n            time.getMinute(),\n            true);\n    timePickerDialog.show();\n\n}\n<\/code><\/pre>\n
You were greatly overcomplicating things. I recommend:<\/p>\n
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  1. Don\u2019t use strings for dates or times in your business logic, use date and time objects. This also means you\u2019ve got no need for a formatter like SimpleDateFormat<\/code> (which, I might add, is notoriously troublesome, so it is good that you can do without it).<\/li>\n
  2. Use java.time<\/code>, the modern Java date and time API. It is so much nicer to work with than the old-fashioned date and time classes like Calendar<\/code>.<\/li>\n<\/ol>\n
    The two points go hand in hand in the above snippets. Also as far as I can see you have no use for the Calendar<\/code> object (c<\/code>) in setDateField<\/code>, just remove it and all use of it.<\/p>\n
    What went wrong in your code?<\/h2>\n
    The culprit was your SimpleDateFormat<\/code>. Try using it like this:<\/p>\n
        SimpleDateFormat f = new SimpleDateFormat(\"yyyy\/mm\/dd HH:mm\");\n    System.out.println(f.parse(\"2018\/04\/17 12:45\"));\n<\/code><\/pre>\n
    On my computer this prints<\/p>\n
    Wed Jan 17 12:45:00 CET 2018\n<\/code><\/pre>\n
    It prints a date in January no matter what is in the string. This is because you tried lowercase mm<\/code> for month. mm<\/code> is for minutes (which you also used correctly), month is uppercase MM<\/code>. So your formatter cannot parse a month at all and assigns your date the default month, which is the first month of the year, January. And this date in January was of course also what went into your millesecond value.<\/p>\n
    Question: Can I use java.time<\/code> on Android?<\/h2>\n
    Yes, you can use java.time<\/code> on Android. Using it just requires Java 6<\/strong>.<\/p>\n