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Java provides certain classes called wrapper classes in the java.lang package. The objects of these classes wrap primitive datatypes within them.Using wrapper classes, you can also add primitive datatypes to various Collection objects such as ArrayList, HashMap etc. You can also pass primitive values over network using wrapper classes.ExampleLive Demoimport java.util.Scanner; public class WrapperExample { public static void main(String args[]){ Scanner sc = new Scanner(System.in); System.out.println("Enter an integer value: "); int i = sc.nextInt(); //Wrapper class of an integer Integer obj ... Read More
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Just like classes you can extend one interface from another using the extends keyword. You can also extend multiple interfaces from an interface using the extends keyword, by separating the interfaces using comma (, ) as −interface MyInterface extends ArithmeticCalculations, MathCalculations{ExampleFollowing is the Java program demonstrating, how to extend multiple interfaces from a single interface.interface ArithmeticCalculations{ public abstract int addition(int a, int b); public abstract int subtraction(int a, int b); } interface MathCalculations { public abstract double ... Read More
To match a regular expression with the given string You need to:.Compile the regular expression of the compile() method of the Pattern class.Get the Matcher object bypassing the required input string as a parameter to the matcher() method of the Pattern class.The matches() method of the Matcher class returns true if a match occurs else it returns false. Therefore, invoke this method to validate the data.ExampleFollowing is a Java regular expression example matches only dateLive Demoimport java.util.ArrayList; import java.util.List; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Sample { public static void main(String args[]){ //Creating the list to ... Read More
The java.text.SimpleDateFormat class is used to format and parse a string to date and date to string.One of the constructors of this class accepts a String value representing the desired date format and creates SimpleDateFormat object. To parse/convert a string as a Date object Instantiate this class by passing desired format string.Parse the date string using the parse() method.You can get the epoch time using the getTime() method.ExampleLive Demoimport java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; public class Sample { public static void main(String args[]) throws ParseException { //Instantiating the SimpleDateFormat class SimpleDateFormat dateformatter = new ... Read More
The getTime() method of the Date class retrieves and returns the epoch time (number of milliseconds from Jan 1st 1970 00:00:00 GMT0.ExampleLive Demoimport java.util.Date; public class Sample { public static void main(String args[]){ //Instantiating the Date class Date date = new Date(); long msec = date.getTime(); System.out.println("Milli Seconds: "+msec); } }OutputMilli Seconds: 1605160094688The getTimeInMillis() method of the calendar class retrieves and returns the time in milli seconds from the epochepoch time (Jan 1st 1970 00:00:00 GMT).ExampleLive Demoimport java.util.Calendar; public class Sample { public static ... Read More
A temporal field is a field of date-time, such as month-of-year or hour-of-minute. These fields are represented by the TemporalField interface and the ChronoField class implements this interface.Following are the list of various temporal fields regarding date supported by the ChronoField class −FieldDescriptionALIGNED_DAY_OF_WEEK_IN_MONTHThis field represents the day of the week with in a month.ALIGNED_DAY_OF_WEEK_IN_YEARThis field represents the aligned day of a week in an year.ALIGNED_WEEK_OF_MONTHThis field represents the aligned wee of a month.ALIGNED_WEEK_OF_YEARThis field represents the aligned week of an year.DAY_OF_MONTHThis field represents the day of a month.DAY_OF_WEEKThis field represents the day of a week.DAY_OF_YEARThis field represents the day of ... Read More
A temporal field is a field of date-time, such as month-of-year or hour-of-minute. These fields are represented by the TemporalField interface and the ChronoField class implements this interface.Following are the list of various temporal fields regarding time supported by the ChronoField class −FieldDescriptionCLOCK_HOUR_OF_AMPMThis field represents the clock hour of a day (am/pm).AMPM_OF_DAYThis field represents the ap/pm of the day.CLOCK_HOUR_OF_DAYThis field represents the clock hour of a day.HOUR_OF_AMPMThis field represents the hour of a day (am/pm).HOUR_OF_DAYThis field represents the hour of a day.INSTANT_SECONDSThis field represents the instant epoch seconds.MICRO_OF_DAYThis field represents the micro of a day.MICRO_OF_SECONDThis field represents the micro of ... Read More
In general, the elapsed time is the time from the starting point to ending point of an event. Following are various ways to find elapsed time in Java −The nanoTime() method returns the current time in nano seconds. To find the elapsed time for the execution of a method in nano seconds −Retrieve the current time using the nanoTime() method.Execute the desired method.Again, retrieve the current time using the nanoTime() method.Finally, Find the difference between the end value and the start value.ExampleLive Demopublic class Example { public void test(){ int num = 0; for(int i=0; i
In general, the elapsed time or, execution is the time from the starting point to ending point of an event. Following are various ways to find elapsed time in Java −The currentTimeMillis() method returns the current time in milliseconds. To find the elapsed time for a method you can get the difference between time values before and after the execution of the desired method.The nanoTime() method returns the current time in nano seconds. To find the elapsed time for a method you can get the difference between time values before and after the execution of the desired method.The now() method ... Read More
In general, the elapsed time is the time from the starting point to ending point of an event. Following are various ways to find elapsed time in Java −Using the currentTimeMillis() methodThe currentTimeMillis() method returns the current time in milliseconds. To find the elapsed time for a method you can get the difference between time values before and after the execution of the desired method.ExampleLive Demopublic class Example { public void test(){ int num = 0; for(int i=0; i