Use the remove() method to remove an element from IdentityHashMap.Let us create IdentityHashMap and add some elementsMap m = new IdentityHashMap(); m.put("1", 100); m.put("2", 200); m.put("3", 300); m.put("4", 150); m.put("5", 110); m.put("6", 50); m.put("7", 90); m.put("8", 250); m.put("9", 350); m.put("10", 450);Let’s say you need to remove 2 from the Map. For that, use the remove() methodm.remove("2");The following is an example to remove an element from Java IdentityHashMapExample Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       Map m = new IdentityHashMap(); m.put("1", 100); ... Read More

Check whether a Map is empty or not using the isEmpty() method.Let us first create a IdentityHashMap and add some elements to itMap m= new IdentityHashMap(); m.put("1", 100); m.put("2", 200); m.put("3", 300); m.put("4", 150); m.put("5", 110); m.put("6", 50); m.put("7", 90); m.put("8", 250); m.put("9", 350); m.put("10", 450);Now, use the following method to check whether the Map is empty or not. Since we added some elements above, therefore the Map is not emptyn.isEmpty();Example Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       Map m = new IdentityHashMap(); m.put("1", 100); m.put("2", 200); m.put("3", 300); m.put("4", 150); ... Read More

The floorKey() method is used to get floor key i.e. to return the greatest key less than or equal to the given key, or null if there is no such key.The following is an example to get floor key from NavigableMapExample Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       NavigableMap n = new TreeMap();       n.put("A", 498);       n.put("B", 389);       n.put("C", 868);       n.put("D", 988);       n.put("E", 686);       n.put("F", 888);       n.put("G", 999);       ... Read More

The first and last elements of a Linked List can be obtained using the methods java.util.LinkedList.getFirst() and java.util.LinkedList.getLast() respectively. Neither of these methods require any parameters.A program that demonstrates this is given as followsExample Live Demoimport java.util.LinkedList; public class Demo { public static void main(String[] args) { LinkedList l = new LinkedList(); l.add("John"); l.add("Sara"); l.add("Susan"); l.add("Betty"); l.add("Nathan"); ... Read More

The lowerEntry() method in NavigabelMap returns a key-value mapping associated with the greatest key strictly less than the given key.The following is an example to implement lowerEntry() methodExample Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       NavigableMap n = new TreeMap();       n.put(5, "Tom");       n.put(9, "John");       n.put(14, "Jamie");       n.put(1, "Tim");       n.put(4, "Jackie");       n.put(15, "Kurt");       n.put(19, "Tiger");       n.put(24, "Jacob");       System.out.println("NavigableMap elements..."+n);       System.out.println("Lower Entry is ... Read More

The higherEntry() method in NavigableMap returns a key-value mapping associated with the least key strictly greater than the given key.The following is an example to implement higherEntry() method −Example Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       NavigableMap n = new TreeMap();       n.put(5, "Tom");       n.put(9, "John");       n.put(14, "Jamie");       n.put(1, "Tim");       n.put(4, "Jackie");       n.put(15, "Kurt");       n.put(19, "Tiger");       n.put(24, "Jacob");       System.out.println("NavigableMap elements..."+n);       System.out.println("Higher Entry ... Read More

Use the put() method to add elements to LinkedHashMap collection.First, let us create a LinkedHashMap −LinkedHashMap l = new LinkedHashMap();Now, add elements −l.put("1", "Jack"); l.put("2", "Tom"); l.put("3", "Jimmy"); l.put("4", "Morgan"); l.put("5", "Tim"); l.put("6", "Brad");The following is an example to add elements to LinkedHashMap collection −Example Live Demoimport java.util.LinkedHashMap; public class Demo { public static void main(String[] args) { LinkedHashMap l = new LinkedHashMap(); l.put("1", "Jack"); l.put("2", "Tom"); l.put("3", "Jimmy"); ... Read More

Firstly, create a HashMap −HashMap hm = new HashMap();Add some elements to the HashMap −hm.put("Shirts", new Integer(700)); hm.put("Trousers", new Integer(600)); hm.put("Jeans", new Integer(1200)); hm.put("Android TV", new Integer(450)); hm.put("Air Purifiers", new Integer(300)); hm.put("Food Processors", new Integer(950));Now, sort the HashMap based on keys using TreeMap −Map sort = new TreeMap(hm); System.out.println("Sorted Map based on key = "+sort);The following is an example to sort HasMap based on keys −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { HashMap hm = new HashMap(); hm.put("Shirts", new ... Read More

In this article, we will learn how to use the contains() method in Java's HashSet class to check whether specific elements are present in a set. We'll create a HashSet, add some elements to it, and verify the existence of given elements using the contains() method. Problem Statement Write a Java program to check if a specific element exists in a HashSet using the contains() method. Below is the demostration of the same − Input Elements in set = [33, 66, 67, 54, 88, 90, 30, 79] Output Elements in set = [33, 66, 67, 54, 88, 90, 30, 79] ... Read More

The synchronizedSet() method returns a synchronized (thread-safe) sorted set backed by the specified sorted set.First, create a HashSet and add elements −Set hs = new HashSet(); hs.add(29); hs.add(879); hs.add(88); hs.add(788); hs.add(456);Now, to get synchronized set, use the synchronizedSet() method −Set s = Collections.synchronizedSet(hs);The following is an example to get synchronized set from HashSet −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { Set hs = new HashSet(); hs.add(29); hs.add(879); ... Read More