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Articles on Trending Technologies
Technical articles with clear explanations and examples
Insert the specified element at the specified position in Java CopyOnWriteArrayList
Using the add() method, insert the specified element at the specified position in the CopyOnWriteArrayList.The syntax is as followsvoid add(int index, E ele)Here, the parameter index is where you want to insert the element and ele is the element to be inserted to this list. To work with CopyOnWriteArrayList class, you need to import the following packageimport java.util.concurrent.CopyOnWriteArrayList;The following is an example to add elements in the CopyOnWriteArrayList class in JavaExampleimport java.util.concurrent.CopyOnWriteArrayList; public class Demo { public static void main(String[] args) { CopyOnWriteArrayList arrList = new CopyOnWriteArrayList(); arrList.add(100); arrList.add(250); ...
Read MoreComplex numbers in C++
In this section we will see how to create and use complex numbers in C++. We can create complex number class in C++, that can hold the real and imaginary part of the complex number as member elements. There will be some member functions that are used to handle this class.In this example we are creating one complex type class, a function to display the complex number into correct format. Two additional methods to add and subtract two complex numbers etc.Example#include using namespace std; class complex { int real, img; public: complex() { ...
Read MoreReplace an element from a Java List using ListIterator
Let us first create a Java List and add elements −ArrayList < String > list = new ArrayList < String > (); list.add("Katie"); list.add("Tom"); list.add("Jack"); list.add("Amy"); list.add("Andre"); list.add("Brad"); list.add("Peter"); list.add("Bradley");Now, use ListIterator and return the next element in the List with next() −ListIteratoriterator = list.listIterator(); iterator.next();Replace the element in the List with set() method. Here, whatever element is set will get replaced as the first element of the Iterator −iterator.set("Angelina");Exampleimport java.util.ArrayList; import java.util.ListIterator; public class Demo { public static void main(String[] args) { ArrayListlist = new ArrayList(); list.add("Katie"); list.add("Tom"); ...
Read MoreC++ Program to Create the Prufer Code for a Tree
Prufer code uniquely identifies a tree which is given by user as a graph representation with labels from 1 to p. This tree consist p(value is given by user) labels of node. It has sequence of p – 2 values.AlgorithmBegin Declare i, j, ver, edg, minimum, p to the integer datatype. Print “Enter the number of vertexes: ”. Enter the value of ver. Initialize edg = ver-1. Declare EDG[edg][2], DG[ver+1] to the integer datatype. Initialize DG[ver+1] = {0}. Print “This tree has (value of edg) edges for (value of ver) vertexes”. ...
Read MoreProvider getVersion() method in Java
The version number of the provider can be obtained using the method getVersion() in the class java.security.Provider. This method requires no parameter and it returns the version number of the provider as required.A program that demonstrates this is given as follows −Exampleimport java.security.*; import java.util.*; public class Demo { public static void main(String[] argv) { try { KeyPairGenerator kpGenerator = KeyPairGenerator.getInstance("DSA"); Provider p = kpGenerator.getProvider(); System.out.println("The version number is: " + p.getVersion()); } catch (NoSuchAlgorithmException e) { ...
Read MoreJava Program to create String to super class type mapping
Here, we have a superclass Vehicle and within that some subclasses −class Vehicle { } class Motorcycle extends Vehicle { } class Bus extends Vehicle { } class Car extends Vehicle { }Now, we will create some strings for mapping with super class type −Mapmap = new HashMap(); map.put("motorcycle", new Motorcycle()); map.put("bus", new Bus()); map.put("car", new Car());Exampleimport java.util.HashMap; import java.util.Map; class Vehicle { } class Motorcycle extends Vehicle { } class Bus extends Vehicle { } class Car extends Vehicle { } public class Demo { public static void main(String... args) { Mapmap = new HashMap(); ...
Read MoreExtract values from HashMap in Java
To extract values from HashMap, let us first create a HashMap with keys and values −HashMapm = new HashMap();Now, add some elements to the HashMap −m.put(10, 20); m.put(30, 40); m.put(50, 60); m.put(70, 80); m.put(90, 100); m.put(110, 120); m.put(130, 140); m.put(150, 160);Now, extract the values from the HashMap −for (Integer i: m.keySet()) { System.out.println(m.get(i)); }Exampleimport java.util.HashMap; public class Demo { public static void main(String args[]) { HashMapm = new HashMap(); m.put(10, 20); m.put(30, 40); m.put(50, 60); m.put(70, 80); m.put(90, 100); ...
Read MoreIs it possible to assign a reference to "this" in java?
The "this" keyword in Java is used as a reference to the current object, within an instance method or a constructor. Using it, you can refer the members of a class such as constructors, variables, and methods.Assigning reference to "this"According to the definition "this" is a keyword which acts as a reference to the current object (the object from whose constructor/method you are using it), its value id is fixed. Therefore, you cannot assign a new reference value to it. Moreover, it is just a keyword, not a variable.Still, if you try to it assign a reference value to "this" it ...
Read MoreHow to keep the insertion order with Java LinkedHashMap?
To keep the insertion order with LinkedHashMap, use Iterator. Let us first create a HashMap and add elements to it −LinkedHashMaplHashMap = new LinkedHashMap(); lHashMap.put("1", "A"); lHashMap.put("2", "B"); lHashMap.put("3", "C"); lHashMap.put("4", "D"); lHashMap.put("5", "E"); lHashMap.put("6", "F"); lHashMap.put("7", "G"); lHashMap.put("8", "H"); lHashMap.put("9", "I");Now, get the values with the values() method. Iterate through the elements and display them −Collection collection = lHashMap.values(); Iterator i = collection.iterator(); while (i.hasNext()) { System.out.println(i.next()); }Exampleimport java.util.Collection; import java.util.Iterator; import java.util.LinkedHashMap; public class Demo { public static void main(String[] args) { LinkedHashMaplHashMap = new LinkedHashMap(); lHashMap.put("1", "A"); ...
Read MoreWhat happens if we call "super()" in a constructor without extending any class, in java?
A super keyword is a reference of the superclass object in Java. Using this, you can invoke the instance methods constructors and, variables, of a superclass.Calling the constructor of a superclassYou can call the constructor of a superclass from the subclass’s constructor.ExampleConsider the following example, it has two classes SuperClass class and SubClass where the SubClass extends the SuperClass. The superclass has a parameterized constructor, we are invoking it from the subclass using the "super" keyword.class SuperClass{ SuperClass(int data){ System.out.println("Superclass's constructor: "+data); } } public class SubClass extends SuperClass{ SubClass(int data) { super(data); ...
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