Conversion from 12 hours time to 24 hours time in java

Question

In my app, I have a requirement to format 12 hours time to 24 hours time. What is the method I have to use?

For example, time like 10

Answer 1

I was looking for same thing but in number, means from integer xx hour, xx minutes and AM/PM to 24 hour format xx hour and xx minutes, so here what i have done:

private static final int AM = 0;
private static final int PM = 1;
/**
   * Based on concept: day start from 00:00AM and ends at 11:59PM, 
   * afternoon 12 is 12PM, 12:xxAM is basically 00:xxAM
   * @param hour12Format
   * @param amPm
   * @return
   */
  private int get24FormatHour(int hour12Format,int amPm){
    if(hour12Format==12 && amPm==AM){
      hour12Format=0;
    }
    if(amPm == PM && hour12Format!=12){
      hour12Format+=12;
    }
    return hour12Format;
  }`

    private int minutesTillMidnight(int hour12Format,int minutes, int amPm){
        int hour24Format=get24FormatHour(hour12Format,amPm);
        System.out.println("24 Format :"+hour24Format+":"+minutes); 
        return (hour24Format*60)+minutes;
      }

Answer 2

Assuming that you use SimpleDateFormat implicitly or explicitly, you need to use H instead of h in the format string.

E.g

HH:mm:ss

instead of

hh:mm:ss

Answer 3

12 to 24 hour time conversion and can be reversed if change time formate in output and input SimpleDateFormat class parameter

Test Data Input:

String input = "07:05:45PM"; timeCoversion12to24(input);

output

19:05:45

 public static String timeCoversion12to24(String twelveHoursTime) throws ParseException {

        //Date/time pattern of input date (12 Hours format - hh used for 12 hours)
        DateFormat df = new SimpleDateFormat("hh:mm:ssaa");

        //Date/time pattern of desired output date (24 Hours format HH - Used for 24 hours)
        DateFormat outputformat = new SimpleDateFormat("HH:mm:ss");
        Date date = null;
        String output = null;

        //Returns Date object
        date = df.parse(twelveHoursTime);

        //old date format to new date format
        output = outputformat.format(date);
        System.out.println(output);

        return output;
    }

Answer 4

Using LocalTime in Java 8, LocalTime has many useful methods like getHour() or the getMinute() method,

For example,

LocalTime intime = LocalTime.parse(inputString, DateTimeFormatter.ofPattern("h:m a"));
String outtime = intime.format(DateTimeFormatter.ISO_LOCAL_TIME);

In some cases, First line alone can do the required parsing

Answer 5

This is the extract of code that I have done.

    String s="08:10:45";
    String[] s1=s.split(":");
    int milipmHrs=0;
    char[] arr=s1[2].toCharArray();
    boolean isFound=s1[2].contains("PM");
    if(isFound){
        int pmHrs=Integer.parseInt(s1[0]);
        milipmHrs=pmHrs+12;
        return(milipmHrs+":"+s1[1]+":"+arr[0]+arr[1]);
    }
    else{

        return(s1[0]+":"+s1[1]+":"+arr[0]+arr[1]);
    }

Answer 6

I have written a simple utility function.

public static String convert24HourTimeTo12Hour(String timeStr) {
    try {
        DateFormat inFormat = new SimpleDateFormat( "HH:mm:ss");
        DateFormat outFormat = new SimpleDateFormat( "hh:mm a");
        Date date = inFormat.parse(timeStr);
        return outFormat.format(date);
    }catch (Exception e){}

    return "";
}