Getting the Day from a Date in Java

Java is a popular programming language used in the development of applications across various platforms. When working with dates, it is often necessary to extract specific information such as the day of the week from a given date. In this section, we will discuss how to get the day from a date in Java.

Java provides the java.util.Calendar class, which represents a calendar. It provides various methods to extract information from a date. The get() method of the Calendar class can be used to extract the day of the week from a given date.

Here's an example that demonstrates how to get the day of the week from a given date in Java:

GetDayFromDate.java

Output:

Day of the week: 7

In this example, we first create a Date object representing May 6, 2023, using the Date constructor that takes the number of milliseconds since January 1, 1970. We then create a Calendar object and set it to the given date using the setTime() method. Finally, we use the get() method of the Calendar object to extract the day of the week and print it to the console.

The get() method of the Calendar class returns an integer representing the day of the week, where 1 represents Sunday, 2 represents Monday, and so on. To print the day of the week as a string, we can use a switch statement or an array of strings to map the integer to the corresponding day of the week.

Here's an example that demonstrates how to print the day of the week as a string:

GetDayFromDate.java

Output:

Day of the week: Saturday

In this example, we first create a Date object and a Calendar object as before. We then use an array of strings to map the integer representing the day of the week to the corresponding string. We subtract 1 from the integer before using it as an index into the array because the array is zero-indexed. Finally, we print the day of the week as a string to the console. It's important to note that the Calendar class in Java has some drawbacks and limitations. For example, it's not thread-safe, and the API can be difficult to work with due to its complex design. Additionally, the Calendar class only supports dates up to the year 2037, after which it will no longer function correctly.

Java introduced the java.time package in Java 8, which provides a modern date and time API. The java.time package includes the LocalDate class, which represents a date without a time component. The LocalDate class provides a getDayOfWeek() method that returns an instance of the DayOfWeek enum, which provides a more convenient and type-safe way to represent the day of the week.

Getting the day of the week from a given date in Java is straightforward using the java.util.Calendar class. We can use the get() method of the `Calendar class to extract the day of the week as an integer and then map it to the corresponding string using an array or a switch statement. By using these methods, we can easily extract the day of the week from a date and use it in our applications as needed.