为界面添加默认方法，演示2

import java.time.LocalDate;

import java.time.LocalDateTime;

import java.time.LocalTime;/*from n o w j a v a . c o m - 时  代  Java*/


class SimpleTimeClient implements TimeClient {


    private LocalDateTime dateAndTime;


    public SimpleTimeClient() {

        dateAndTime = LocalDateTime.now();

    }


    public void setTime(int hour, int minute, int second) {
    /**
     * n o w    j a v a  . c o m 提 供 
    **/

        LocalDate currentDate = LocalDate.from(dateAndTime);

        LocalTime timeToSet = LocalTime.of(hour, minute, second);

        dateAndTime = LocalDateTime.of(currentDate, timeToSet);

    }


    public void setDate(int day, int month, int year) {

        LocalDate dateToSet = LocalDate.of(day, month, year);

        LocalTime currentTime = LocalTime.from(dateAndTime);

        dateAndTime = LocalDateTime.of(dateToSet, currentTime);

    }


    public void setDateAndTime(int day, int month, int year, int hour,

            int minute, int second) {

        LocalDate dateToSet = LocalDate.of(day, month, year);

        LocalTime timeToSet = LocalTime.of(hour, minute, second);

        dateAndTime = LocalDateTime.of(dateToSet, timeToSet);

    }


    public LocalDateTime getLocalDateTime() {

        return dateAndTime;

    }


    public String toString() {

        return dateAndTime.toString();

    }


    public static void main(String... args) {

        TimeClient myTimeClient = new SimpleTimeClient();

        System.out.println(myTimeClient.toString());

    }

}

interface TimeClient {

    public void setTime(int hour, int minute, int second);


    public void setDate(int day, int month, int year);


    public void setDateAndTime(int day, int month, int year, int hour,

            int minute, int second);

}


public class Main {

    public static void main(String... args) {

        TimeClient myTimeClient = new SimpleTimeClient();

        System.out.println("Current time: " + myTimeClient.toString());

    }

}