Class RelativeDateTimeFormatter

java.lang.Object
org.graalvm.shadowed.com.ibm.icu.text.RelativeDateTimeFormatter
public final class RelativeDateTimeFormatter extends Object
Formats simple relative dates. There are two types of relative dates that it handles:
  • relative dates with a quantity e.g "in 5 days"
  • relative dates without a quantity e.g "next Tuesday"

This API is very basic and is intended to be a building block for more fancy APIs. The caller tells it exactly what to display in a locale independent way. While this class automatically provides the correct plural forms, the grammatical form is otherwise as neutral as possible. It is the caller's responsibility to handle cut-off logic such as deciding between displaying "in 7 days" or "in 1 week." This API supports relative dates involving one single unit. This API does not support relative dates involving compound units. e.g "in 5 days and 4 hours" nor does it support parsing. This class is both immutable and thread-safe.

Here are some examples of use: 

 RelativeDateTimeFormatter fmt = RelativeDateTimeFormatter.getInstance();
 fmt.format(1, Direction.NEXT, RelativeUnit.DAYS); // "in 1 day"
 fmt.format(3, Direction.NEXT, RelativeUnit.DAYS); // "in 3 days"
 fmt.format(3.2, Direction.LAST, RelativeUnit.YEARS); // "3.2 years ago"

 fmt.format(Direction.LAST, AbsoluteUnit.SUNDAY); // "last Sunday"
 fmt.format(Direction.THIS, AbsoluteUnit.SUNDAY); // "this Sunday"
 fmt.format(Direction.NEXT, AbsoluteUnit.SUNDAY); // "next Sunday"
 fmt.format(Direction.PLAIN, AbsoluteUnit.SUNDAY); // "Sunday"

 fmt.format(Direction.LAST, AbsoluteUnit.DAY); // "yesterday"
 fmt.format(Direction.THIS, AbsoluteUnit.DAY); // "today"
 fmt.format(Direction.NEXT, AbsoluteUnit.DAY); // "tomorrow"

 fmt.format(Direction.PLAIN, AbsoluteUnit.NOW); // "now"

The Style parameter allows selection of different length styles: LONG ("3 seconds ago"), SHORT ("3 sec. ago"), NARROW ("3s ago"). In the future, we may add more forms, such as relative day periods ("yesterday afternoon"), etc.

  • Method Details

    • getInstance

      public static RelativeDateTimeFormatter getInstance()
      Returns a RelativeDateTimeFormatter for the default locale.

    • getInstance

      public static RelativeDateTimeFormatter getInstance(ULocale locale)
      Returns a RelativeDateTimeFormatter for a particular locale.
      Parameters:
      locale - the locale.
      Returns:
      An instance of RelativeDateTimeFormatter.

    • getInstance

      public static RelativeDateTimeFormatter getInstance(Locale locale)
      Returns a RelativeDateTimeFormatter for a particular Locale.
      Parameters:
      locale - the Locale.
      Returns:
      An instance of RelativeDateTimeFormatter.

    • getInstance

      public static RelativeDateTimeFormatter getInstance(ULocale locale, NumberFormat nf)
      Returns a RelativeDateTimeFormatter for a particular locale that uses a particular NumberFormat object.
      Parameters:
      locale - the locale
      nf - the number format object. It is defensively copied to ensure thread-safety and immutability of this class.
      Returns:
      An instance of RelativeDateTimeFormatter.

    • getInstance

      public static RelativeDateTimeFormatter getInstance(ULocale locale, NumberFormat nf, RelativeDateTimeFormatter.Style style, DisplayContext capitalizationContext)
      Returns a RelativeDateTimeFormatter for a particular locale that uses a particular NumberFormat object, style, and capitalization context
      Parameters:
      locale - the locale
      nf - the number format object. It is defensively copied to ensure thread-safety and immutability of this class. May be null.
      style - the style.
      capitalizationContext - the capitalization context.

    • getInstance

      public static RelativeDateTimeFormatter getInstance(Locale locale, NumberFormat nf)
      Returns a RelativeDateTimeFormatter for a particular Locale that uses a particular NumberFormat object.
      Parameters:
      locale - the Locale
      nf - the number format object. It is defensively copied to ensure thread-safety and immutability of this class.
      Returns:
      An instance of RelativeDateTimeFormatter.

    • format

      public String format(double quantity, RelativeDateTimeFormatter.Direction direction, RelativeDateTimeFormatter.RelativeUnit unit)
      Formats a relative date with a quantity such as "in 5 days" or "3 months ago". This method returns a String. To get more information about the formatting result, use formatToValue().
      Parameters:
      quantity - The numerical amount e.g 5. This value is formatted according to this object's NumberFormat object.
      direction - NEXT means a future relative date; LAST means a past relative date.
      unit - the unit e.g day? month? year?
      Returns:
      the formatted string
      Throws:
      IllegalArgumentException - if direction is something other than NEXT or LAST.

    • formatToValue

      public RelativeDateTimeFormatter.FormattedRelativeDateTime formatToValue(double quantity, RelativeDateTimeFormatter.Direction direction, RelativeDateTimeFormatter.RelativeUnit unit)
      Formats a relative date with a quantity such as "in 5 days" or "3 months ago". This method returns a FormattedRelativeDateTime, which exposes more information than the String returned by format().
      Parameters:
      quantity - The numerical amount e.g 5. This value is formatted according to this object's NumberFormat object.
      direction - NEXT means a future relative date; LAST means a past relative date.
      unit - the unit e.g day? month? year?
      Returns:
      the formatted relative datetime
      Throws:
      IllegalArgumentException - if direction is something other than NEXT or LAST.

    • formatNumeric

      public String formatNumeric(double offset, RelativeDateTimeFormatter.RelativeDateTimeUnit unit)
      Format a combination of RelativeDateTimeUnit and numeric offset using a numeric style, e.g. "1 week ago", "in 1 week", "5 weeks ago", "in 5 weeks". This method returns a String. To get more information about the formatting result, use formatNumericToValue().
      Parameters:
      offset - The signed offset for the specified unit. This will be formatted according to this object's NumberFormat object.
      unit - The unit to use when formatting the relative date, e.g. RelativeDateTimeUnit.WEEK, RelativeDateTimeUnit.FRIDAY.
      Returns:
      The formatted string (may be empty in case of error)

    • formatNumericToValue

      public RelativeDateTimeFormatter.FormattedRelativeDateTime formatNumericToValue(double offset, RelativeDateTimeFormatter.RelativeDateTimeUnit unit)
      Format a combination of RelativeDateTimeUnit and numeric offset using a numeric style, e.g. "1 week ago", "in 1 week", "5 weeks ago", "in 5 weeks". This method returns a FormattedRelativeDateTime, which exposes more information than the String returned by formatNumeric().
      Parameters:
      offset - The signed offset for the specified unit. This will be formatted according to this object's NumberFormat object.
      unit - The unit to use when formatting the relative date, e.g. RelativeDateTimeUnit.WEEK, RelativeDateTimeUnit.FRIDAY.
      Returns:
      The formatted string (may be empty in case of error)

    • format

      public String format(RelativeDateTimeFormatter.Direction direction, RelativeDateTimeFormatter.AbsoluteUnit unit)
      Formats a relative date without a quantity. This method returns a String. To get more information about the formatting result, use formatToValue().
      Parameters:
      direction - NEXT, LAST, THIS, etc.
      unit - e.g SATURDAY, DAY, MONTH
      Returns:
      the formatted string. If direction has a value that is documented as not being fully supported in every locale (for example NEXT_2 or LAST_2) then this function may return null to signal that no formatted string is available.
      Throws:
      IllegalArgumentException - if the direction is incompatible with unit this can occur with NOW which can only take PLAIN.

    • formatToValue

      public RelativeDateTimeFormatter.FormattedRelativeDateTime formatToValue(RelativeDateTimeFormatter.Direction direction, RelativeDateTimeFormatter.AbsoluteUnit unit)
      Formats a relative date without a quantity. This method returns a FormattedRelativeDateTime, which exposes more information than the String returned by format().
      Parameters:
      direction - NEXT, LAST, THIS, etc.
      unit - e.g SATURDAY, DAY, MONTH
      Returns:
      the formatted string. If direction has a value that is documented as not being fully supported in every locale (for example NEXT_2 or LAST_2) then this function may return null to signal that no formatted string is available.
      Throws:
      IllegalArgumentException - if the direction is incompatible with unit this can occur with NOW which can only take PLAIN.

    • format

      public String format(double offset, RelativeDateTimeFormatter.RelativeDateTimeUnit unit)
      Format a combination of RelativeDateTimeUnit and numeric offset using a text style if possible, e.g. "last week", "this week", "next week", "yesterday", "tomorrow". Falls back to numeric style if no appropriate text term is available for the specified offset in the object’s locale. This method returns a String. To get more information about the formatting result, use formatToValue().
      Parameters:
      offset - The signed offset for the specified field.
      unit - The unit to use when formatting the relative date, e.g. RelativeDateTimeUnit.WEEK, RelativeDateTimeUnit.FRIDAY.
      Returns:
      The formatted string (may be empty in case of error)

    • formatToValue

      public RelativeDateTimeFormatter.FormattedRelativeDateTime formatToValue(double offset, RelativeDateTimeFormatter.RelativeDateTimeUnit unit)
      Format a combination of RelativeDateTimeUnit and numeric offset using a text style if possible, e.g. "last week", "this week", "next week", "yesterday", "tomorrow". Falls back to numeric style if no appropriate text term is available for the specified offset in the object’s locale. This method returns a FormattedRelativeDateTime, which exposes more information than the String returned by format().
      Parameters:
      offset - The signed offset for the specified field.
      unit - The unit to use when formatting the relative date, e.g. RelativeDateTimeUnit.WEEK, RelativeDateTimeUnit.FRIDAY.
      Returns:
      The formatted string (may be empty in case of error)

    • combineDateAndTime

      public String combineDateAndTime(String relativeDateString, String timeString)
      Combines a relative date string and a time string in this object's locale. This is done with the same date-time separator used for the default calendar in this locale.
      Parameters:
      relativeDateString - the relative date e.g 'yesterday'
      timeString - the time e.g '3:45'
      Returns:
      the date and time concatenated according to the default calendar in this locale e.g 'yesterday, 3:45'

    • getNumberFormat

      public NumberFormat getNumberFormat()
      Returns a copy of the NumberFormat this object is using.
      Returns:
      A copy of the NumberFormat.

    • getCapitalizationContext

      public DisplayContext getCapitalizationContext()
      Return capitalization context.
      Returns:
      The capitalization context.

    • getFormatStyle

      public RelativeDateTimeFormatter.Style getFormatStyle()
      Return style
      Returns:
      The formatting style.