In -depth analysis of Java Date Framework: inheritance and usage of Date class

In -depth analysis of Java Date Framework: inheritance and usage of Date class In the Java programming language, date and time processing is a very common demand.To meet this needs, Java provides a strong set of date and time processing framework.Among them, the Date class is one of the cores of the Java date framework, which is used to represent a specific moment. The inheritance relationship of the date class: The Date class is an abstract class, which is located under the Java.util package.This class has inherited the Object class and is a parent class of all dates and time -related classes. Date class usage: 1. Create Date object: You can use a non -constructor function to create a DATE object that represents the current date and time.For example: Date now = new Date(); You can also use a constructor with a Long -type parameter with a specific date and time to create a date object.The parameters indicate the milliseconds that started from midnight (Greenwich Standard Time) on January 1, 1970.For example: Date specificDate = new Date(1627944000000L); 2. Get date and time information: The Date class provides many methods to obtain information on date and time, such as year, month, days, hours, minutes and seconds.For example: int year = specificDate.getYear() + 1900; int month = specificDate.getMonth() + 1; int day = specificDate.getDate(); int hours = specificDate.getHours(); int minutes = specificDate.getMinutes(); int seconds = specificDate.getSeconds(); It should be noted that the Getyear () method returns to the year of 1900, so it is necessary to add 1900 corrections; and the month range of the getmonth () method returned is 0-11, so it needs to be added 1 to correct. 3. Date and time comparison: The Date class provides some ways to compare the date and time.Among them, the most commonly used method is the compareto () method.This method compares the current DATE object with another Date object that is introduced, and returns an integer value to indicate the sequential relationship between the two objects.If the current object is earlier than the other object, the negative number is returned; if the two objects are equal, it returns 0; if the current object is later than another object, the positive number is returned.For example: Date date1 = new Date(1627944000000L); Date date2 = new Date(1628030400000L); int result = date1.compareTo(date2); 4. Date and time formatting: The Tostring () method of the Date class will output the date and time in the default format.If you need to display the date and time according to the custom format, you can use the SimpleDateFormat class.For example: Date date = new Date(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String formattedDate = sdf.format(date); The above code formats the current date and time into the form of "yyyy-MM-DD HH: MM: SS". Summarize: Through in -depth analysis of the inheritance and usage of the Date class, we can understand the basic concepts and usage methods of the Java date framework.The Date class can be used to represent a specific moment and provide a series of methods to handle the date and time -related operation.However, it should be noted that because the DATE class is not safe, it is necessary to pay attention to synchronization problems when using in a multi -threaded environment.In development, it is recommended to use the new date and time API (class under the java.time package) introduced by Java 8 to replace the Date class because it provides richer features and better thread security.