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");Example Live Demoimport 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 ... Read More

To check capacity in Java, firstly create a list and add elements. After that use ensureCapacity() and increase the capacity.Let us first create an ArrayList and add some elements −ArrayListarrList = new ArrayList(5); arrList.add(100); arrList.add(200); arrList.add(300); arrList.add(400); arrList.add(500);Now, increase the capacity of the ArrayList −arrList.ensureCapacity(15);Meanwhile, with the size() method, you can check the current size of the ArrayList as well.Example Live Demoimport java.util.ArrayList; public class Demo {    public static void main(String[] a) {       ArrayListarrList = new ArrayList(5);       arrList.add(100);       arrList.add(200);       arrList.add(300);       arrList.add(400);       arrList.add(500); ... Read More

Create a Date object −Date date = new Date();Now, set the ZonedId to default −final ZoneId id = ZoneId.systemDefault();Convert java.util.date to ZonedDateTime −System.out.println(ZonedDateTime.ofInstant(date.toInstant(), id));Example Live Demoimport java.time.ZoneId; import java.time.ZonedDateTime; import java.util.Date; public class Demo {    public static void main(String[] args) {       Date date = new Date();       final ZoneId id = ZoneId.systemDefault();       System.out.println(ZonedDateTime.ofInstant(date.toInstant(), id));    } }Output2019-04-19T00:37:33.344+05:30[Asia/Calcutta]

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.Example Live Demoimport 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 More

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.Example Live Demoimport 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 More

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);Example Live Demoimport 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]

In this article, we will learn how to calculate the frequency of words in a text using Java and Lambda Expressions. By leveraging concise syntax and functional programming techniques, we can efficiently process text data and determine word occurrences. This approach is particularly useful for applications like text analysis and natural language processing. What is Lambda Expression? A lambda expression in Java is a concise way to represent an anonymous function(a function without a name). Introduced in Java 8, it simplifies the implementation of functional interfaces (interfaces with a single abstract method), enabling cleaner and more readable code. Syntax of ... Read More

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.Example Live Demoimport 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 More

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));Example Live Demoimport 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 More

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