Java的日期與時間類別放在："java.util.Date"裡面，使用前先要import進來：

import java.util.Date;

Java的Date類別一共有兩個建構函數(constructor)，預設沒有參數，會產生當前的時間。另一個是帶一個參數，參數是以微秒(milliseconds)為單位的數字，指距離1970年1月1日之後多久。

因此要取得當前時間，只需要：

Date date = new Date();

想要輸出時間則要先轉為字串(String)：

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

以下是Date類別支持的方法(methods)：

1	boolean after(Date date)
Returns true if the invoking Date object contains a date that is later than the one specified by date, otherwise, it returns false.
2	boolean before(Date date)
Returns true if the invoking Date object contains a date that is earlier than the one specified by date, otherwise, it returns false.
3	Object clone( )
Duplicates the invoking Date object.
4	int compareTo(Date date)
Compares the value of the invoking object with that of date. Returns 0 if the values are equal. Returns a negative value if the invoking object is earlier than date. Returns a positive value if the invoking object is later than date.
5	int compareTo(Object obj)
Operates identically to compareTo(Date) if obj is of class Date. Otherwise, it throws a ClassCastException.
6	boolean equals(Object date)
Returns true if the invoking Date object contains the same time and date as the one specified by date, otherwise, it returns false.
7	long getTime( )
Returns the number of milliseconds that have elapsed since January 1, 1970.
8	int hashCode( )
Returns a hash code for the invoking object.
9	void setTime(long time)
Sets the time and date as specified by time, which represents an elapsed time in milliseconds from midnight, January 1, 1970
10	String toString( )
Converts the invoking Date object into a string and returns the result.