In this article, we will learn to generate random numbers with restrictions in Java. We will be using the Java Random class from java.util package. Random class Random class is imported from java.util package. The instance of this class is used to generate the random numbers and provides different numbers of different types integer, double, long, float, etc. Steps to generate random numbers with restrictions Following are the steps to generate random numbers with restrictions − Import the Random class from the java.util package. Initialize the Random object to generate random values. ... Read More

To evaluate mathematical string to int, use Nashorn JavaScript in Java i.e. scripting. Nashorn invoke dynamics feature, introduced in Java 7 to improve performance.For scripting, use the ScriptEngineManager class for the engine:ScriptEngineManager scriptEngineManager = new ScriptEngineManager(); ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("nashorn");Now, use put() to set a key/value pair in the state of the ScriptEngine:scriptEngine.put("one", 10); scriptEngine.put("two", 50); scriptEngine.put("three", 40);Now, here is the mathematical string. Use eval to evaluate:String strExp = "(one + two - three) == 20"; Object evalExp = scriptEngine.eval(strExp);Exampleimport javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; public class Demo {    public static void main(String[] args) {       ScriptEngineManager ... Read More

Firstly, declare a Long array list and add some elements to it:ArrayList < Long > arrList = new ArrayList < Long > (); arrList.add(100000 L); arrList.add(200000 L); arrList.add(300000 L); arrList.add(400000 L); arrList.add(500000 L);Now, set the same size for the newly created long array:final long[] arr = new long[arrList.size()]; int index = 0;Each and every element of the Long array list is assigned to the long array:for (final Long value : arrList) {    arr[index++] = value; }Exampleimport java.util.ArrayList; public class Demo {    public static void main(String[] args) {       ArrayList

In this article, we'll explore how to determine the start and end dates of a week using Java. Specifically, we'll write a program that takes a given date and calculates the Monday and Sunday of that week.  Problem Statement Write a Java program to find the beginning (Monday) and end (Sunday) dates of the week for a given date. Input Date = 2019-04-16 Output Start of the Week = 2019-04-15End of the Week = 2019-04-21 Steps to calculate week's start and end dates Following are the steps to get the beginning and end date of the week − ... Read More

Let us first set two dates:LocalDate date1 = LocalDate.of(2019, 4, 16); LocalDate date2 = date1.with(Month.MAY).withDayOfMonth(04);Now, count the dates between both the above dates using between():int numDays = Period.between(date1, date2).getDays();Exampleimport java.time.LocalDate; import java.time.Month; import java.time.Period; public class Demo {    public static void main(String[] argv) {       LocalDate date1 = LocalDate.of(2019, 4, 16);       LocalDate date2 = date1.with(Month.MAY).withDayOfMonth(04);       int numDays = Period.between(date1, date2).getDays();       System.out.println("Number of days between two dates = "+numDays);    } }OutputNumber of days between two dates = 18

At first, display the current date:LocalDate date = LocalDate.now();Now, get the day of week from the above Date (current date):DayOfWeek day = DayOfWeek.of(date.get(ChronoField.DAY_OF_WEEK));On the basis of the above result, use SWITCH to check for the current day. If the day is SATURDAY/SUNDAY, then it’s Weekend.Exampleimport java.time.DayOfWeek; import java.time.temporal.ChronoField; import java.time.LocalDate; public class Demo {    public static void main(String[] argv) {       LocalDate date = LocalDate.now();       DayOfWeek day = DayOfWeek.of(date.get(ChronoField.DAY_OF_WEEK));       switch (day) {          case SATURDAY:             System.out.println("Weekend - Saturday");         ... Read More

Set the two Java dates:LocalDate date1 = LocalDate.of(2019, 3, 25); LocalDate date2 = LocalDate.of(2019, 4, 29);Now, get the difference between two dates with Period class between() method:Period p = Period.between(date1, date2);Now, get the years, month and days:p.getYears() p.getMonths() p.getDays()Exampleimport java.time.LocalDate; import java.time.Period; public class Demo {    public static void main(String[] args) {       LocalDate date1 = LocalDate.of(2019, 3, 25);       LocalDate date2 = LocalDate.of(2019, 4, 29);       System.out.println("Date 1 = "+date1);       System.out.println("Date 2 = "+date2);       Period p = Period.between(date1, date2);       System.out.println("Period = "+p);   ... Read More

In this program, we will learn to add a specific period to a date using Java’s LocalDate class. By using Java's Period class, we can specify an amount of time (such as months and days) and then add this period to a LocalDate. The program demonstrates how to set a period and apply it to a given date to get a new, updated date. Steps to add Period to LocalDate  Following are the steps to add Period to LocalDate − Import LocalDate and Period from java.time package to work with dates and periods. ... Read More

Let us first set an Instant:Instant now = Instant.ofEpochMilli(184142540078l);Let us now minus seconds from Instant:Instant resSeconds = now.minusSeconds(50);Let us now minus nanoseconds from Instant:Instant resNanoSeconds = now.minusNanos(10000);Exampleimport java.time.Instant; public class Demo {    public static void main(String[] args) {       Instant now = Instant.ofEpochMilli(184142540078l);       System.out.println(now);       Instant resSeconds = now.minusSeconds(50);       System.out.println("After subtracting seconds = "+resSeconds);       Instant resNanoSeconds = now.minusNanos(10000);       System.out.println("After subtracting nanoseconds = "+resNanoSeconds);    } }Output1975-11-02T06:42:20.078Z After subtracting seconds = 1975-11-02T06:41:30.078Z After subtracting nanoseconds = 1975-11-02T06:42:20.077990Z

The following are the two Instant timestamps:Instant one = Instant.ofEpochSecond(1355836728); Instant two = Instant.ofEpochSecond(1355866935);Get the Duration between both the Instant:Duration res = Duration.between(one, two);Now, get the seconds between the two timestamps:long seconds = res.getSeconds();Now, get the minutes between the two timestamps:long minutes = res.abs().toMinutes();Exampleimport java.time.Duration; import java.time.Instant; public class Demo {    public static void main(String[] args) {       Instant one = Instant.ofEpochSecond(1355836728);       Instant two = Instant.ofEpochSecond(1355866935);       Duration res = Duration.between(one, two);       System.out.println(res);       long seconds = res.getSeconds();       System.out.println("Seconds between Durations = "+seconds);   ... Read More