java8 CheckDate示例演示使用自定义时态查询的两种方法

import java.time.Month;
import java.time.Year;
import java.time.LocalDate;
import java.time.DateTimeException;
import java.time.temporal.TemporalQuery;
import java.time.temporal.TemporalAccessor;
import java.io.PrintStream;
public class CheckDate {
    public static void main(String[] args) {
        Month month = null;
        LocalDate date = null;
        if (args.length < 2)
        {
            System.out.printf("Usage: CheckDate <month> <day>%n");
            throw new IllegalArgumentException();
        }
        try {
            month = Month.valueOf(args[0].toUpperCase());
        } catch (IllegalArgumentException exc) {
            System.out.printf("%s is not a valid month.%n", args[0]);
            throw exc;    // Rethrow the exception.
        }
        int day = Integer.parseInt(args[1]);
        try {
            date = LocalDate.of(Year.now().getValue(), month, day);
        } catch (DateTimeException exc) {
            System.out.printf("%s %s is not a valid date.%n", month, day);
            throw exc;     // Rethrow the exception.
        }
        // 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);
    }
}

import java.time.Month;
import java.time.Year;
import java.time.LocalDate;
import java.time.DateTimeException;
import java.time.temporal.TemporalQuery;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.ChronoField;
import java.io.PrintStream;
import java.lang.Boolean;
public 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.
    // 如果传入日期恰好处于家庭假期的时间段内，返回true
    // 因为查询比较的是月份和日份，即使针对是不同类型“期间”，检查也会成功
    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;
    }
}

import java.time.Month;
import java.time.Year;
import java.time.LocalDate;
import java.time.DateTimeException;
import java.time.temporal.TemporalQuery;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.ChronoField;
import java.io.PrintStream;
import java.lang.Boolean;
public 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;
    }
}