Java中的 TimeUnit toNanos() 方法及示例

TimeUnit 类的toNanos()方法用于获取从 1970 年 1 月 1 日午夜 UTC 以来 TimeUnit 对象表示的时间，以 NanoSeconds 的数量表示。
句法：

public long toNanos(long duration)

参数：此方法接受一个强制参数duration ，它是以毫秒为单位的持续时间。
返回值：此方法将转换后的持续时间返回为 NanoSeconds。
下面的程序说明了 TimeUnit toNanos() 方法的实现：
方案一：

Java

// Java program to demonstrate
// toNanos() method of TimeUnit Class
 
import java.util.concurrent.*;
import java.util.Date;
 
class GFG {
    public static void main(String args[])
    {
        // Get current time in milliseconds
        long timeInMilliSec = new Date().getTime();
 
        // Create a TimeUnit object
        TimeUnit time = TimeUnit.MILLISECONDS;
 
        // Convert milliseconds to NanoSeconds
        // using toNanos() method
        System.out.println("Time " + timeInMilliSec
                           + " milliSeconds in NanoSeconds = "
                           + time.toNanos(timeInMilliSec));
    }
}

输出：

Time 1539585501608 milliSeconds in NanoSeconds = 1539585501608000000

方案二：

Java

// Java program to demonstrate
// toNanos() method of TimeUnit Class
 
import java.util.concurrent.*;
import java.util.Calendar;
 
class GFG {
    public static void main(String args[])
    {
        // Get current time in milliseconds
        long timeInMilliSec = Calendar
                                  .getInstance()
                                  .getTimeInMillis();
 
        // Create a TimeUnit object
        TimeUnit time = TimeUnit.MILLISECONDS;
 
        // Convert milliseconds to NanoSeconds
        // using toNanos() method
        System.out.println("Time " + timeInMilliSec
                           + " milliSeconds in NanoSeconds = "
                           + time.toNanos(timeInMilliSec));
    }
}

输出：

Time 1539585503771 milliSeconds in NanoSeconds = 1539585503771000000