Get the TreeMap size using the size() method.First, create a TreeMap and add elements to it −TreeMap m = new TreeMap(); m.put(1, "PHP"); m.put(2, "jQuery"); m.put(3, "JavaScript"); m.put(4, "Ruby"); m.put(5, "Java"); m.put(6, "AngularJS"); m.put(7, "ExpressJS");Count the number of elements in the above TreeMap or get the size using the size() method as shown below −m.size()To get the size of TreeMap, the following is the code −Example Live Demoimport java.util.*; public class Demo {    public static void main(String args[]) {       TreeMap m = new TreeMap();       m.put(1, "PHP");       m.put(2, "jQuery");       ... Read More

In this article, we will learn how to retrieve the highest key stored in a TreeMap. We will create a simple Java program that demonstrates how to create a TreeMap, add key-value pairs to it, and then use the lastKey() method to find the highest key in the map. Problem Statement Write a Java program to get the highest key stored in TreeMap. Input {1=PHP, 2=jQuery, 3=JavaScript, 4=Ruby, 5=Java, 6=AngularJS, 7=ExpressJS} Output Highest key in TreeMap: 7 Steps  The followingare the steps to get the highest key in TreeMap − First, import the classes. ... Read More

The last element of a Linked List can be retrieved using the method java.util.LinkedList.getLast() respectively. This method does not require any parameters and it returns the last element of the LinkedList.A program that demonstrates this is given as follows −Example Live Demoimport java.util.LinkedList; public class Demo {    public static void main(String[] args) {       LinkedList l = new LinkedList();       l.add("Andy");       l.add("Sara");       l.add("James");       l.add("Betty");       l.add("Bruce");       System.out.println("The last element of the Linked List is : " + l.getLast());    } }OutputThe last ... Read More

The first element can be deleted from a LinkedList by using the method java.util.LinkedList.removeFirst(). This method does not have any parameters and it returns the first element of the LinkedList.The last element can be deleted from a LinkedList by using the method java.util.LinkedList.removeLast(). This method does not have any parameters and it returns the last element of the LinkedList.A program that demonstrates this is given as follows −Example Live Demoimport java.util.LinkedList; public class Demo {    public static void main(String[] args) {       LinkedList l = new LinkedList();       l.add("Apple");       l.add("Mango");       ... Read More

In general, a linked list is a linear data structure that is a collection of "nodes". Each node contains data and a pointer pointing to the next node. A doubly linked list contains an extra pointer pointing to the previous node, and using this, we can traverse forwards as well as backwards. LinkedList in Java In Java, a linked list is represented by the class named LinkedList. It is a part of the Java Collection Framework, and it belongs to the java.util package. This class implements two interfaces, namely, List and Deque. In this article, we will learn how to ... Read More

Use the firstKey() method to get the lowest key stored in TreeMap.Let us first set the TreeMap and add some elements to it −TreeMap m = new TreeMap(); m.put(1, "PHP"); m.put(2, "jQuery"); m.put(3, "JavaScript"); m.put(4, "Ruby"); m.put(5, "Java"); m.put(6, "AngularJS"); m.put(7, "ExpressJS");Now get the lowest key −m.firstKey()The following is an example to get the lowest key in TreeMap −Example Live Demoimport java.util.*; public class Demo {    public static void main(String args[]) {       TreeMap m = new TreeMap();       m.put(1, "PHP");       m.put(2, "jQuery");       m.put(3, "JavaScript");       m.put(4, "Ruby"); ... Read More

Use the headMap() method in Java to get ahead map. It returns a view of the portion of this map whose keys are less than or equal to.Let’s say you need to get the portion of the map above the set map (and not inclusive of it). For that, use the headMap() method like this −m.headMap(4)If you want the value 4 to be included as well, then set it as true −m.headMap(4, true)The following is an example to get Head Map from Java TreeMap −Example Live Demoimport java.util.*; public class Demo {    public static void main(String args[]) {     ... Read More

In this article, we will learn to check if a particular value exists in TreeMap in Java. A Java TreeMap is an ordered map that keeps key-value pairs in ascending order of keys. Although it is efficient to look up a key, checking for a value is inefficient since one has to iterate over the values. What is TreeMap? A TreeMap is a Red-Black tree-based implementation it is a part of java.util package and implements the NavigableMap interface. It maintains the natural ordering of keys or a custom order defined by a Comparator. Since it is sorted by keys, searching ... Read More

To check if a particular key exists in TreeMap, use the containsKey() method.Create a TreeMap first and add some elements −TreeMap m = new TreeMap(); m.put(1, "PHP"); m.put(2, "jQuery"); m.put(3, "JavaScript"); m.put(4, "Ruby"); m.put(5, "Java"); m.put(6, "AngularJS"); m.put(7, "ExpressJS");Now, let’s say we need to check that key 5 exists or not. For that, set the containsKey() method like this −m.containsKey(5)The following is an example to check if a particular key exists in TreeMap −Example Live Demoimport java.util.*; public class Demo {    public static void main(String args[]) {       TreeMap m = new TreeMap();       m.put(1, "PHP"); ... Read More

Let us create TreeMap in Java. It stores unique elements in ascending order −TreeMap m = new TreeMap();Now let us add some elements −m.put(1, "PHP"); m.put(2, "jQuery"); m.put(3, "JavaScript"); m.put(4, "Ruby"); m.put(5, "Java"); m.put(6, "AngularJS"); m.put(7, "ExpressJS");The following is an example to create a TreeMap −Example Live Demoimport java.util.*; public class Demo {    public static void main(String args[]) {       TreeMap m = new TreeMap();       m.put(1, "PHP");       m.put(2, "jQuery");       m.put(3, "JavaScript");       m.put(4, "Ruby");       m.put(5, "Java");       m.put(6, "AngularJS");       ... Read More