The simplest way to create a Java Priority Queue to ignore duplicates is to first create a Set implementation −HashSet set = new HashSet (); set.add(100); set.add(150); set.add(250); set.add(300); set.add(250); set.add(500); set.add(600); set.add(500); set.add(900);Now, create Priority Queue and include the set to remove duplicates in the above set −PriorityQueuequeue = new PriorityQueue(set);Example Live Demoimport java.util.HashSet; import java.util.PriorityQueue; public class Demo {    public static void main(String[] args) {       HashSetset = new HashSet();       set.add(100);       set.add(150);       set.add(250);       set.add(300);       set.add(250);       set.add(500); ... Read More

Let us first create a List in Java −Listlist = new ArrayList(); list.add("A"); list.add("B"); list.add("C");Now to convert the above list to read-only, use Collections −list = Collections.unmodifiableList(list);We have converted the above list to read-only. Now, if you will try to add more elements to the list, then the following error would be visible −Exception in thread "main" java.lang.Error: Unresolved compilation problem:Example Live Demoimport java.util.ArrayList; import java.util.Collections; import java.util.List; public class Demo {    public static void main(String args[]) throws Exception {       Listlist = new ArrayList();       list.add("A");       list.add("B");       list.add("C");   ... Read More

In this article, we will demonstrate how to create a new list of employee names from an existing list of Employee objects using Lambda Expressions. We will utilize Java’s Stream API to efficiently map the employee data and collect it into a new list. Lambda Expressions: Lambda expressions simplify functional programming by working with functional interfaces, which have only one method. A lambda expression provides a way to implement this method easily. Steps Following are the steps to create a new list with values from existing list with Lambda Expressions − Import the necessary classes ... Read More

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 −Example Live Demoimport 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, ... Read More

In this article, we will learn how to use a LinkedHashSet in Java to add and remove elements while maintaining the insertion order. You will see how elements are stored, removed, and updated in a LinkedHashSet without altering the sequence in which they were added. Problem Statement Write a Java program to add elements to a LinkedHashSet, remove specific elements, and display the updated set while ensuring the insertion order of the elements remains unchanged. Below is a demonstration of the same − Input Set = [20, 60, 80, 120, 150, 200, 220, 260, 380] Output Set = [20, 60, ... Read More

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);Example Live Demoimport 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 ... Read More

In this article, we will learn how to use the Properties class in Java to store and display key-value pairs. The Properties class is useful for handling configuration settings or storing data in a structured way, where both keys and values are strings. By using the put() method, we can easily add values to a property list and later retrieve or display these key-value pairs. This approach provides a simple and efficient way to manage data in a key-value format in Java applications. Problem Statement A properties list contains country-year pairs. Write a Java program to store values ... Read More

In this article, we will learn how to convert a Properties list into a Map in Java. The Properties class is commonly used to store key-value pairs, but sometimes you may need to work with these pairs in a Map structure. We will demonstrate how to take the properties and convert them into a HashMap. Problem Statement Write a program in Java to convert the properties list into a Map structure − Output Key and Value of the Map... P: 1 Q: 2 R: 3 S: 4 T: 5 U: 6 V: 7 Steps to convert the properties list into ... Read More

To get Tail Map from TreeMap, let us first create a TreeMap and set key-value pair −TreeMaptMap = new TreeMap(); tMap.put("1", "A"); tMap.put("2", "B"); tMap.put("3", "C"); tMap.put("4", "D"); tMap.put("5", "E"); tMap.put("6", "F"); tMap.put("7", "G");Now, let’s say you need to get the tailmap from 2 i.e. all the key-value pairs after 2. For that, use the method tailMap() −SortedMapmap = tMap.tailMap("2");Example Live Demoimport java.util.SortedMap; import java.util.TreeMap; public class Demo {    public static void main(String[] args) {       TreeMaptMap = new TreeMap();       tMap.put("1", "A");       tMap.put("2", "B");       tMap.put("3", "C");       ... Read More

Two lists are equal if they consist of same number of elements in the same order.Let’s say we have the following two lists −ListarrList1 = Arrays.asList(new Integer[] { 10, 20, 30, 45, 55, 70, 90, 100 }); ListarrList2 = Arrays.asList(new Integer[] {15, 25, 35, 50, 55, 75, 95, 120});Now, let’s find out whether both the lists are equal or not −arrList1.equals(arrList2);If both the above lists have equal elements, then TRUE is returned, else FALSE is the return value.Example Live Demoimport java.util.Arrays; import java.util.List; public class Demo {    public static void main(String[] a) {       ListarrList1 = Arrays.asList(new Integer[] ... Read More