The isEmpty() method is used in Java to check whether a NavigableMap is empty or not.First, create a NavigableMap and add elements to it −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");Now, check whether the Map is empty or not −System.out.println("Map is empty? " + n.isEmpty());The following is an example to implement isEmpty() method and check whether the Map is empty −Example Live Demoimport java.util.*; public class Demo {    public static void main(String[] args) {       NavigableMap n = new TreeMap();       n.put(5, ... Read More

To create a Sorted Set, firstly create a Set −Set s = new HashSet();Add elements to the above set −int a[] = {77, 23, 4, 66, 99, 112, 45, 56, 39, 89}; Set s = new HashSet(); try {    for(int i = 0; i < 5; i++) {    s.add(a[i]); }After that, use TreeSet class to sort −TreeSet sorted = new TreeSet(s);Get the last element, using the last() method −System.out.println("Last element of the sorted set = "+ (Integer)sorted.last());The following is the code to get the last element from a Sorted Set in Java −Example Live Demoimport java.util.*; public class Demo ... Read More

Fetch and remove the first element in Queue using the poll() method.Create a queue −Queue q = new LinkedList();Add some elements −q.add("abc"); q.add("def"); q.add("ghi"); q.add("jkl"); q.add("mno"); q.add("pqr"); q.add("stu"); q.add("vwx");Now, remove the first element −q.poll()The following is an example to implement the poll() method −Example Live Demoimport java.util.LinkedList; import java.util.Queue; public class Demo {    public static void main(String[] args) {       Queue q = new LinkedList();       q.add("abc");       q.add("def");       q.add("ghi");       q.add("jkl");       q.add("mno");       q.add("pqr");       q.add("stu");       q.add("vwx");   ... Read More

To remove an element from a Queue, use the remove() method.First, set a Queue and insert some elements −Queue q = new LinkedList(); q.offer("abc"); q.offer("def"); q.offer("ghi"); q.offer("jkl"); q.offer("mno"); q.offer("pqr"); q.offer("stu"); q.offer("vwx");Remove the first element −System.out.println("Queue head = " + q.element()); System.out.println("Removing element from queue = " + q.remove());The following is an example −Example Live Demoimport java.util.LinkedList; import java.util.Queue; public class Demo {    public static void main(String[] args) {       Queue q = new LinkedList();       q.offer("abc");       q.offer("def");       q.offer("ghi");       q.offer("jkl");       q.offer("mno");       q.offer("pqr"); ... Read More

The element() method in Java Queues is used to return the element at the front of the container and does not remove it.The following is an example. Firstly, create a Queue and add some elements −Queue q = new LinkedList(); q.offer("abc"); q.offer("def"); q.offer("ghi"); q.offer("jkl"); q.offer("mno"); q.offer("pqr"); q.offer("stu"); q.offer("vwx");Now use the element() method as shown below −System.out.println("Queue head = " + q.element());The following is the complete example −Example Live Demoimport java.util.LinkedList; import java.util.Queue; public class Demo {    public static void main(String[] args) {       Queue q = new LinkedList();       q.offer("abc");       q.offer("def");     ... Read More

An element in an Java LinkedList can be replaced using the java.util.ArrayList.set() method. This method has two parameters i.e the index at which the LinkedList element is to be replaced and the element that it should be replaced with. ArrayList.set() method returns the element that was at the position specified at the index previously.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("Pear");       l.add("Apple");       l.add("Mango");       l.add("Guava"); ... Read More

A LinkedList can be converted into an ArrayList by creating an ArrayList such that the parameterized constructor of the ArrayList initialises it with the elements of the LinkedList.A program that demonstrates this is given as follows −Example Live Demoimport java.util.ArrayList; import java.util.LinkedList; import java.util.List; public class Demo {    public static void main(String[] args) {       LinkedList l = new LinkedList();       l.add("Orange");       l.add("Apple");       l.add("Peach");       l.add("Guava");       l.add("Pear");       List aList = new ArrayList(l);       System.out.println("The ArrayList elements are: ");     ... Read More

To create a queue using LinkedList class, try the following −Queue q = new LinkedList(); q.offer("abc"); q.offer("def"); q.offer("ghi"); q.offer("jkl"); q.offer("mno"); q.offer("pqr"); q.offer("stu"); q.offer("vwx");After that to print the elements, you need to use check a condition for Queue as shown below −Object ob; while ((ob = q.poll()) != null) {    System.out.println(ob); }The following is an example −Example Live Demoimport java.util.LinkedList; import java.util.Queue; public class Demo {    public static void main(String[] args) {       Queue q = new LinkedList();       q.offer("abc");       q.offer("def");       q.offer("ghi");       q.offer("jkl");       q.offer("mno"); ... Read More

The current method name that contains the execution point that is represented by the current stack trace element is provided by the java.lang.StackTraceElement.getMethodName() method.A program that demonstrates this is given as follows −Example Live Demopublic class Demo {    public static void main(String args[]) {       System.out.println       ("The method name is: " + new Exception().getStackTrace()[0].getMethodName());    } }OutputThe method name is: mainNow let us understand the above program.The method getMethodName() is used to obtain the current method name that contains the execution point that is represented by the current stack trace element. This is printed using ... Read More

The methods of an object can be called using the java.lang.Class.getDeclaredMethods() method. This method returns an array that contains all the Method objects with public, private, protected and default access. However, the inherited methods are not included.Also, the getDeclaredMethods() method returns a zero length array if the class or interface has no methods or if a primitive type, array class or void is represented in the Class object.A program that demonstrates this is given as follows −Example Live Demoimport java.lang.reflect.Method; class ClassA {    private String name = "John";    public String returnName() {       return name;    } ... Read More