Java Date Time - LocalDate query(TemporalQuery query) example

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LocalDate query(TemporalQuery<R> query) queries this date using the specified query.

Syntax

query has the following syntax.

public <R> R query(TemporalQuery<R> query)

Example

The following example shows how to use query.

import java.time.LocalDate;
import java.time.temporal.TemporalQueries;
//from   w  ww  .  j av a2s.  c o  m
public class Main {
  public static void main(String[] args) {
    LocalDate a = LocalDate.of(2014, 6, 30);
    LocalDate b = a.query(TemporalQueries.localDate());
    System.out.println(b);
  }
}

The code above generates the following result.

Example 2

The following code shows how to query date using a lambda expression.

import java.time.LocalDate;
import java.time.Month;
import java.time.Year;
import java.time.temporal.ChronoField;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalQuery;
/*w  ww  .  j  a  v  a2  s.  c o  m*/
public class Main {
    public static void main(String[] args) {
        Month month = Month.valueOf("MARCH");

        int day = 10;
        LocalDate date = LocalDate.of(Year.now().getValue(), month, day);

        // Invoking the query without using a lambda expression.
        Boolean isFamilyVacation = date.query(new FamilyVacations());

        // Invoking the query using a lambda expression.
        Boolean isFamilyBirthday = date.query(FamilyBirthdays::isFamilyBirthday);

        if (isFamilyVacation.booleanValue() || isFamilyBirthday.booleanValue())
            System.out.printf("%s is an important date!%n", date);
        else
            System.out.printf("%s is not an important date.%n", date);
    }
}

class FamilyBirthdays {
  
  // Returns true if the passed-in date is the same as one of the
  // family birthdays. Because the query compares the month and day only,
  // the check succeeds even if the Temporal types are not the same.
  public static Boolean isFamilyBirthday(TemporalAccessor date) {
      int month = date.get(ChronoField.MONTH_OF_YEAR);
      int day   = date.get(ChronoField.DAY_OF_MONTH);
      
      // Angie's birthday is on April 3.
      if ((month == Month.APRIL.getValue()) && (day == 3))
          return Boolean.TRUE;

      // Sue's birthday is on June 18.
      if ((month == Month.JUNE.getValue()) && (day == 18))
          return Boolean.TRUE;

      // Joe's birthday is on May 29.
      if ((month == Month.MAY.getValue()) && (day == 29))
          return Boolean.TRUE;

      return Boolean.FALSE;
  }
}

class FamilyVacations implements TemporalQuery<Boolean> {
  
  // Returns true if the passed-in date occurs during one of the
  // family vacations. Because the query compares the month and day only,
  // the check succeeds even if the Temporal types are not the same.
  public Boolean queryFrom(TemporalAccessor date) {
      int month = date.get(ChronoField.MONTH_OF_YEAR);
      int day   = date.get(ChronoField.DAY_OF_MONTH);
      
      // Disneyland over Spring Break
      if ((month == Month.APRIL.getValue()) && ((day >= 3) && (day <= 8)))
          return Boolean.TRUE;

      // Smith family reunion on Lake Saugatuck
      if ((month == Month.AUGUST.getValue()) && ((day >= 8) && (day <= 14)))
          return Boolean.TRUE;

      return Boolean.FALSE;
  }
}
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The code above generates the following result.

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