Advanced JAVA - Common APIs of LocalDate class, LocalTime class and LocalDateTime class (6)

Table of contents

API               

      1.0 API description of LocalDate class, LocalTime class and LocalDateTime class

        1.1 HowCreateLocalDate class, LocalTime class, LocalDateTime class objects

        1.2 The LocalDate class, the LocalTime class, and the instance methods starting with  get in the LocalDateTime class

        1.3 LocalDateTime inside toLocalDate() given toLocalTime() Practical method

        1.4 LocalDate class, LocalTime class, LocalDateTime class instance methods starting with with 

        1.5 LocalDate class, LocalTime class, LocalDateTime class instance methods starting with plus 

        1.6 LocalDate class, LocalTime class, LocalDateTime class instance methods starting with minus 

        1.7 LocalDate class, LocalTime class, LocalDateTime class equals(), isBefore(), isAfter() Example methods 

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API               

        1.0 LocalDate LocalTime 类、 Category API DescriptionLocalDateTime

        SinceLocalDate class is different from LocalTime class, The usage of the API of a>LocalDateTime class is roughly the same.

       LocalDate：RepresentativeLocalDate (year, month, day, star period)

        LocalTime: representslocal time (hour, minute, second, nanosecond)

        LocalDateTime: representslocal date and time (year, month, day, week, hour, minutes, seconds, nanoseconds)

        1.1 How to set upLocalDate LocalTime 类、 LocalDateTime Category picture

        Can be created throughclass name.now() static methodcurrent< a i=4>Date, time, datetime objects can also be created throughclass name.of() static methodSpecify date, time, datetime object.  

Create throughclass name.now() static methodcurrentThe object codes of date, time, and date and time are as follows:

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {
    public static void main(String[] args) {

        //创建当前日期对象
        LocalDate localDate = LocalDate.now();
        System.out.println(localDate);

        //创建当前时间对象
        LocalTime localTime = LocalTime.now();
        System.out.println(localTime);

        //创建当前日期、时间对象
        LocalDateTime localDateTime = LocalDateTime.now();
        System.out.println(localDateTime);
    }
}

The running results are as follows:

        

Create throughclassname.of() static methodspecifyThe codes for date, time, and date-time objects are as follows:

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {
    public static void main(String[] args) {

        //创建指定日期对象
        LocalDate localDate = LocalDate.of(2025, 12, 12);
        System.out.println(localDate);

        //创建指定时间对象
        LocalTime localTime = LocalTime.of(9, 30, 12);
        System.out.println(localTime);

        //创建指定日期、时间对象
        //也可以把直接上面的结合起来
        LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime);
        System.out.println(localDateTime);

    }
}

The running results are as follows:

        

        1.2 LocalDate LocalTime 类、Example method for openingget Since the category LocalDateTime

         obtains the corresponding information through the instance method starting with get .

code show as below:

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {
    public static void main(String[] args) {
        //创建当前日期对象
        LocalDate localDate = LocalDate.now();
            //获取到了当前年
       int year = localDate.getYear();
        System.out.println(year);
            //获取到了当前月
        int month = localDate.getMonthValue();
        System.out.println(month);
            //获取到了当前日
        int date = localDate.getDayOfMonth();
        System.out.println(date);
            //获取当前星期几
        int week = localDate.getDayOfWeek().getValue();
        System.out.println(week);


        //创建当前时间对象
        LocalTime localTime = LocalTime.now();
            //获取当前小时
        int hour = localTime.getHour();
        System.out.println(hour);
            //获取当前分钟
        int minute = localTime.getMinute();
        System.out.println(minute);
            //获取当前秒
        int second = localTime.getSecond();
        System.out.println(second);
            //获取当前纳秒
        long a = localTime.getNano();
        System.out.println(a);

        System.out.println("-----------------------------------");
        //创建当前日期、时间对象,其实这类就是上面两个类的集合
        LocalDateTime localDateTime = LocalDateTime.now();
        System.out.println(localDateTime.getYear());
        System.out.println(localDateTime.getMonthValue());
        System.out.println(localDateTime.getDayOfMonth());
        System.out.println(localDateTime.getDayOfWeek().getValue());
        System.out.println(localDateTime.getHour());
        System.out.println(localDateTime.getMinute());
        System.out.println(localDateTime.getSecond());
        System.out.println(localDateTime.getNano());
        
    }
}

The running results are as follows:

        1.3 LocalDateTime within toLocalDate() given toLocalTime() Example method

        A simple understanding is to divide the LocalDateTime class into two parts LocalDate class and LocalTime kind.

The code is as follows:

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {
    public static void main(String[] args) {

        LocalDateTime localDateTime = LocalDateTime.of(2024, 12, 12,
                9, 30, 30, 30);
        System.out.println(localDateTime);

        System.out.println("-----------------------------------");
        LocalDate localDate = localDateTime.toLocalDate();
        System.out.println(localDate);

        LocalTime localTime = localDateTime.toLocalTime();
        System.out.println(localDateTime);

    }
}

The running results are as follows:

        

        1.4 LocalDate LocalTime 类、Example method with Because of the categoryLocalDateTime

        directly modify the corresponding information through the instance method starting with with . It should be noted that the objects created by the above three classes are It isunchangeable, so the modification here refers to a>.   Create a new object     

code show as below:

import java.time.LocalDateTime;
import java.time.LocalDate;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {
    public static void main(String[] args) {

        LocalDate localDate = LocalDate.of(2025,12,12);
        LocalDate reviseLocalDate2 = localDate.withYear(2027);
        LocalDate reviseLocalDate3 = localDate.withMonth(11);
        LocalDate reviseLocalDate4 = localDate.withDayOfMonth(22);

        System.out.println(localDate);
        System.out.println(reviseLocalDate2);
        System.out.println(reviseLocalDate3);
        System.out.println(reviseLocalDate4);

        System.out.println("---------------------------------------------");
        LocalTime localTime = LocalTime.of(11,11,11);
        LocalTime reviseLocalTime2 = localTime.withHour(12);
        LocalTime reviseLocalTime3 = localTime.withMinute(12);
        LocalTime reviseLocalTime4 = localTime.withSecond(12);

        System.out.println(localTime);
        System.out.println(reviseLocalTime2);
        System.out.println(reviseLocalTime3);
        System.out.println(reviseLocalTime4);

        System.out.println("--------------------------------------------");
        LocalDateTime localDateTime = LocalDateTime.of(localDate,localTime);
        LocalDateTime reviseLocalDateTime2 = localDateTime.withYear(2028);
        LocalDateTime reviseLocalDateTime3 = localDateTime.withMonth(3);
        LocalDateTime reviseLocalDateTime4 = localDateTime.withDayOfMonth(9);
        LocalDateTime reviseLocalDateTime5 = localDateTime.withHour(10);
        LocalDateTime reviseLocalDateTime6 = localDateTime.withMinute(11);
        LocalDateTime reviseLocalDateTime7 = localDateTime.withSecond(12);

        System.out.println(localDateTime);
        System.out.println(reviseLocalDateTime2);
        System.out.println(reviseLocalDateTime3);
        System.out.println(reviseLocalDateTime4);
        System.out.println(reviseLocalDateTime5);
        System.out.println(reviseLocalDateTime6);
        System.out.println(reviseLocalDateTime7);
    }
}

The running results are as follows:

        1.5 LocalDate LocalTime 类、Example method plus  Since LocalDateTime

        You can add certain information through the instance method starting with plus . It is important to note that each time you add an object When receiving information, a new object will be returned.

code show as below:

import java.time.LocalDateTime;
import java.time.LocalDate;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2025,12,12);
        LocalDate reviseLocalDate2 = localDate.plusYears(5);
        LocalDate reviseLocalDate3 = localDate.plusMonths(11);
        LocalDate reviseLocalDate4 = localDate.plusDays(22);

        System.out.println(localDate);
        System.out.println(reviseLocalDate2);
        System.out.println(reviseLocalDate3);
        System.out.println(reviseLocalDate4);

        System.out.println("----------------------------------------");
        LocalTime localTime = LocalTime.of(11,11,11);
        LocalTime reviseLocalTime2 = localTime.plusHours(12);
        LocalTime reviseLocalTime3 = localTime.plusMinutes(12);
        LocalTime reviseLocalTime4 = localTime.plusSeconds(12);

        System.out.println(localTime);
        System.out.println(reviseLocalTime2);
        System.out.println(reviseLocalTime3);
        System.out.println(reviseLocalTime4);

        System.out.println("-----------------------------------------");
        LocalDateTime localDateTime = LocalDateTime.of(localDate,localTime);
        LocalDateTime reviseLocalDateTime2 = localDateTime.plusYears(2028);
        LocalDateTime reviseLocalDateTime3 = localDateTime.plusMonths(3);
        LocalDateTime reviseLocalDateTime4 = localDateTime.plusDays(9);
        LocalDateTime reviseLocalDateTime5 = localDateTime.plusHours(10);
        LocalDateTime reviseLocalDateTime6 = localDateTime.plusMinutes(11);
        LocalDateTime reviseLocalDateTime7 = localDateTime.plusSeconds(12);

        System.out.println(localDateTime);
        System.out.println(reviseLocalDateTime2);
        System.out.println(reviseLocalDateTime3);
        System.out.println(reviseLocalDateTime4);
        System.out.println(reviseLocalDateTime5);
        System.out.println(reviseLocalDateTime6);
        System.out.println(reviseLocalDateTime7);
    }
}

The running results are as follows:

        

        1.6 LocalDate LocalTime 类、Example method minus  LocalDateTime

        By using the instance method starting with minus , a certain piece of information can be reduced. It is important to note that each time an object is reduced When receiving information, a new object will be returned.

code show as below:

import java.time.LocalDateTime;
import java.time.LocalDate;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2025,12,12);
        LocalDate reviseLocalDate2 = localDate.minusYears(5);
        LocalDate reviseLocalDate3 = localDate.minusMonths(11);
        LocalDate reviseLocalDate4 = localDate.minusDays(22);

        System.out.println(localDate);
        System.out.println(reviseLocalDate2);
        System.out.println(reviseLocalDate3);
        System.out.println(reviseLocalDate4);

        System.out.println("---------------------------------------");
        LocalTime localTime = LocalTime.of(11,11,11);
        LocalTime reviseLocalTime2 = localTime.minusHours(12);
        LocalTime reviseLocalTime3 = localTime.minusMinutes(12);
        LocalTime reviseLocalTime4 = localTime.minusSeconds(12);

        System.out.println(localTime);
        System.out.println(reviseLocalTime2);
        System.out.println(reviseLocalTime3);
        System.out.println(reviseLocalTime4);

        System.out.println("----------------------------------------");
        LocalDateTime localDateTime = LocalDateTime.of(localDate,localTime);
        LocalDateTime reviseLocalDateTime2 = localDateTime.minusYears(2028);
        LocalDateTime reviseLocalDateTime3 = localDateTime.minusMonths(3);
        LocalDateTime reviseLocalDateTime4 = localDateTime.minusDays(9);
        LocalDateTime reviseLocalDateTime5 = localDateTime.minusHours(10);
        LocalDateTime reviseLocalDateTime6 = localDateTime.minusMinutes(11);
        LocalDateTime reviseLocalDateTime7 = localDateTime.minusSeconds(12);

        System.out.println(localDateTime);
        System.out.println(reviseLocalDateTime2);
        System.out.println(reviseLocalDateTime3);
        System.out.println(reviseLocalDateTime4);
        System.out.println(reviseLocalDateTime5);
        System.out.println(reviseLocalDateTime6);
        System.out.println(reviseLocalDateTime7);
    }
}

The running results are as follows:

        1.7 LocalDate LocalTime 类、Example method equals() , isBefore(), isAfter() in LocalDateTime

        equals()  Used to determine whether the contents of two objects of the same type, such as date, time, and date and time, are the same.

        isBefore()  is used to determine whether the contents of two objects of the same type, such as date, time, date and time, are the objects that call this methodBefore.

        isAfter()  Used to determine whether the contents of two objects of the same type, such as date, time, date and time, are the objects that call this methodAfter.

Take the following code (equals() method as an example):

import java.time.LocalDateTime;
import java.time.LocalDate;
import java.time.LocalTime;

public class LocalDate_LocalTime_LocalDateTime {

    public static void main(String[] args) {
        LocalDate a = LocalDate.of(2023,12,12);
        LocalDate b = LocalDate.of(2023,12,12);
        System.out.println(a.equals(b));

        System.out.println("----------------------------------------");
        LocalTime c = LocalTime.of(9,30,30);
        LocalTime d = LocalTime.of(9,30,30);
        System.out.println(c.equals(d));

        System.out.println("----------------------------------------");
        LocalDateTime e = LocalDateTime.of(a,c);
        LocalDateTime f = LocalDateTime.of(b,d);
        System.out.println(e.equals(f));

    }

}

The running results are as follows:

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        In summary, these types of APIs can be learned comparatively. It is not difficult. You only need to type more code to master them.