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Java Articles
Page 64 of 450
Java Program to check if a Float is Infinite or Not a Number(NAN)
To check if a Float is isInfinite, use the isInfinite() method and to check for NAN, use the isNaN() method.Examplepublic class Demo { public static void main(String[] args) { float value1 = (float) 1 / 0; boolean res1 = Float.isInfinite(value1); System.out.println("Checking for isInfinite? = "+res1); float value2 = (float) Math.sqrt(9); boolean res2 = Float.isNaN(value2); System.out.println("Checking for isNan? = "+res2); } }OutputChecking for isInfinite? = true Checking for isNan? = false
Read MoreHow to display random numbers less than 20 in Java
At first, create a Random class object −Random rand = new Random();Now, create a new array −int num; int arr[] = new int[10];Loop through and set the Random nextInt with 20 as parameter since you want random numbers less than 20 −for (int j = 0; j
Read MoreSet Date value in Java HashMap?
Create a Calendar instance and Date object −Calendar cal = Calendar.getInstance(); Date date = new Date(); cal.setTime(date);Now, create a HashMap and store Date value −LinkedHashMaphashMap = new LinkedHashMap(); hashMap.put("year", cal.get(Calendar.YEAR)); hashMap.put("month", cal.get(Calendar.MONTH)); hashMap.put("day", cal.get(Calendar.DAY_OF_MONTH));Exampleimport java.util.Calendar; import java.util.Date; import java.util.LinkedHashMap; public class Demo { public static void main(String[] argv) { Calendar cal = Calendar.getInstance(); Date date = new Date(); System.out.println("Date = "+date); cal.setTime(date); LinkedHashMaphashMap = new LinkedHashMap(); hashMap.put("year", cal.get(Calendar.YEAR)); hashMap.put("month", cal.get(Calendar.MONTH)); hashMap.put("day", cal.get(Calendar.DAY_OF_MONTH)); ...
Read MoreHow to display numbers in scientific notation in Java?
To display number in scientific notation, create NumberFormat object first −NumberFormat numFormat = newDecimalFormat();Now, let’s say you need to format the minimum value of Integer −int i = Integer.MIN_VALUE; System.out.println(i); numFormat = newDecimalFormat("0.######E0"); System.out.println(numFormat.format(i)); numFormat = newDecimalFormat("0.#####E0"); System.out.println(numFormat.format(i));Above, we have used format() method of the NumberFormat class.Exampleimport java.text.DecimalFormat; import java.text.NumberFormat; public class Demo { public static void main(String args[]) { NumberFormat numFormat = new DecimalFormat(); int i = Integer.MIN_VALUE; System.out.println(i); numFormat = new DecimalFormat("0.######E0"); System.out.println(numFormat.format(i)); numFormat = new DecimalFormat("0.#####E0"); ...
Read MoreHow to extract multiple integers from a String in Java?
Let’s say the following is our string with integer and characters −String str = "(29, 12; 29, ) (45, 67; 78, 80)";Now, to extract integers, we will be using the following pattern −\dWe have set it with Pattern class −Matcher matcher = Pattern.compile("\d+").matcher(str);Exampleimport java.util.ArrayList; import java.util.List; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Demo { public static void main(String[] args) { String str = "(29, 12; 29, ) (45, 67; 78, 80)"; Matcher matcher = Pattern.compile("\d+").matcher(str); Listlist = new ArrayList(); while(matcher.find()) { list.add(Integer.parseInt(matcher.group())); } System.out.println("Integers = "+list); } }OutputIntegers = [29, 12, 29, 45, 67, 78, 80]
Read MoreHow to get the Checksum of a Byte Array in Java?
Create a Byte Array for which you want the Checksum −byte[] arr = "This is it!".getBytes();Now, create a Checksum object −Checksum checksum = new Adler32(); checksum.update(arr, 0, arr.length);The update() above updates the current checksum with the specified array of bytes.Now, get the checksum with getValue() method, which gives the current checksum value.Exampleimport java.util.zip.Adler32; import java.util.zip.Checksum; public class Demo { public static void main(String[] argv) throws Exception { byte[] arr = "This is it!".getBytes(); Checksum checksum = new Adler32(); checksum.update(arr, 0, arr.length); long res = checksum.getValue(); ...
Read MoreJava Program to change a file attribute to writable
Let’s say our file is “input.txt”, which is set read-only −File myFile = new File("input.txt"); myFile.createNewFile(); myFile.setReadOnly();Now, set the above file to writable −myFile.setWritable(true);After that, you can use canWrite() to check whether the file is writable or not.Exampleimport java.io.File; public class Demo { public static void main(String[] args) throws Exception { File myFile = new File("input.txt"); myFile.createNewFile(); myFile.setReadOnly(); if (myFile.canWrite()) { System.out.println("Writable!"); } else { System.out.println("Read only mode!"); } // ...
Read MoreCheck the frequency of an element in Java with Collections.frequency
Create a List in Java −List< String >list = Arrays.asList("P", "Q", "R", "P", "T", "P", "U", "V", "W", "X", "W" );Now, let’s say you want to get the frequency of element P. For that, use the Collections.frequency() method −Collections.frequency(list, "P");A shown above, we can find the occurrence of any letter as well −Collections.frequency(list, "T");Exampleimport java.util.Arrays; import java.util.Collections; import java.util.List; public class Demo { public static void main(String[] args) { Listlist = Arrays.asList("P", "Q", "R", "P", "T", "P", "U", "V", "W", "X", "W" ); int checkOccurrence = Collections.frequency(list, "P"); System.out.println("Occurrence of ...
Read MoreHow to create a Queue from LinkedList in Java?
Let us create a queue from LinkedList like this −Queuequeue = new LinkedList(); queue.add("P"); queue.add("Q"); queue.add("R"); queue.add("S"); queue.add("T"); queue.add("U"); queue.add("V");Now, use a List to display the elements of the queue −Listlist = new ArrayList(queue);Exampleimport java.util.ArrayList; import java.util.LinkedList; import java.util.List; import java.util.Queue; public class Demo { public static void main(String[] args) { Queuequeue = new LinkedList(); queue.add("P"); queue.add("Q"); queue.add("R"); queue.add("S"); queue.add("T"); queue.add("U"); queue.add("V"); Listlist = new ArrayList(queue); for (Object ob: ...
Read MoreJava Program to create a new list with values from existing list with Function Mapper
To create a new list with values from fields from existing list with Function Mapper, the following is an example. Here, we have a class Employee −class Employee { private String emp_name; private int emp_age; private String emp_zone; }The following is an example that creates a new list from existing with Function Mapper −Exampleimport java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.function.Function; public class Demo { public static void main(String args[]) { List < Employee > emp = Arrays.asList(new Employee("Jack", 29, "South"), new Employee("Tom", 24, "North"), new Employee("Harry", 35, "West"), ...
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