Java – 当前日期和时间

在Java中，有一个称为 Date 类的内置类，我们可以导入Java.time 包来使用日期和时间 API。在这里，我们应该打印当前日期和时间。可以有多种方法来打印当前日期和时间。

获取当前日期和时间的不同方法

1. 使用日期类
2. 使用 Calendar 类的 get() 方法
3. 使用日历和格式化程序类以特定格式打印当前日期。

方法一：使用日期类

例子：

Java

// Java Program to Display Current Date and Time
// Using Date class
 
// Importing required classes
import java.util.*;
 
// Class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating object of date class
        Date d1 = new Date();
 
        // Printing the value stored in above object
        System.out.println("Current date is " + d1);
    }
}

输出

Current date is Thu Mar 31 01:14:28 UTC 2022

方法二：使用 Calendar 类的 get() 方法

getInstance() 方法通常用于获取时间、日期或任何需要的属于日历年份的一些内容。

Tip: Whenever we require anyrhing belonging to Calender, Calender class is one of naive base for sure approach to deal with dae and time instances.

例子：

Java

// Java Program to Illustrate getinstance() Method
// of Calendar Class
 
// Importing required classes
import java.util.*;
 
// Class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating an object of Calender class
        Calendar c = Calendar.getInstance();
 
        // Print corresponding instances by passing
        // required some as in arguments
        System.out.println("Day of week : "
                           + c.get(Calendar.DAY_OF_WEEK));
 
        System.out.println("Day of year : "
                           + c.get(Calendar.DAY_OF_YEAR));
 
        System.out.println("Week in Month : "
                           + c.get(Calendar.WEEK_OF_MONTH));
 
        System.out.println("Week in Year : "
                           + c.get(Calendar.WEEK_OF_YEAR));
 
        System.out.println(
            "Day of Week in Month : "
            + c.get(Calendar.DAY_OF_WEEK_IN_MONTH));
 
        System.out.println("Hour : "
                           + c.get(Calendar.HOUR));
 
        System.out.println("Minute : "
                           + c.get(Calendar.MINUTE));
 
        System.out.println("Second : "
                           + c.get(Calendar.SECOND));
 
        System.out.println("AM or PM : "
                           + c.get(Calendar.AM_PM));
 
        System.out.println("Hour (24-hour clock) : "
                           + c.get(Calendar.HOUR_OF_DAY));
    }
}

输出：

Day of week : 7
Day of year : 83
Week in Month : 4
Week in Year : 12
Day of Week in Month : 4
Hour : 6
Minute : 22
Second : 48
AM or PM : 1
Hour (24-hour clock) : 18

方法 3：使用日历和格式化程序类以特定格式打印当前日期。

例子：

Java

// Java Program to Demonstrate Working of SimpleDateFormat
// Class
 
// Importing required classes
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
 
// Class
class GFG {
 
    // Main driver method
    public static void main(String args[])
        throws ParseException
    {
 
        // Formatting as per given pattern in the argument
        SimpleDateFormat ft
            = new SimpleDateFormat("dd-MM-yyyy");
 
        String str = ft.format(new Date());
 
        // Printing the formatted date
        System.out.println("Formatted Date : " + str);
 
        // Parsing a custom string
        str = "02/18/1995";
        ft = new SimpleDateFormat("MM/dd/yyyy");
        Date date = ft.parse(str);
 
        // Printing date as per parsed string on console
        System.out.println("Parsed Date : " + date);
    }
}

输出

Formatted Date : 31-03-2022
Parsed Date : Sat Feb 18 00:00:00 UTC 1995