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Object Oriented Programming Articles
Page 318 of 589
Java Program to Allocate and Initialize Super Class Members using Constructor
In Java, super refers to the parent class instance, and to inherit members of the super class to the child class, we use the extends keyword. Before writing a Java program to allocate and initialize super class members using a constructor, let's go through some concepts we are going to use in this article. What is Constructor? A Java constructor is a class member that initializes instance variables of a class. It is very similar to a method, but the difference is that methods can return a value, but a constructor does not return any value because it can't have any return ...
Read MoreJava Program to Check Armstrong Number
In number theory, an Armstrong number is a pattern-based number whose sum of each digit raised to the power of total number of digits is equal to the given number itself. This article aims to explain Java programs that checks whether the given number is Armstrong or not. How to Check Armstrong Number? To check whether a number is an Armstrong or not, first, determine the total number of digits and assume it 'n'. Then separate each digit and raise them to the power of 'n'. In the last step, calculate the power of each digit and add all ...
Read MoreJava program to check if a given number is perfect number
When the sum of factors of a given number (after discarding the given number) is equal to the number itself is called a perfect number. The sum of these divisors is known as the aliquot sum. Therefore, we can say that a number is perfect if it matches its aliquot sum. All known perfect numbers are even. Problem Statement In this article, we will create Java programs to check if a given number is perfect or not. Let's try to understand the given problem through some examples: Example Scenarios: Input: number = 496 Output: 496 is a perfect number ...
Read MoreJava program to check whether a number is even or odd
We are given an integer number as input, and our task is to write a Java program to check whether that number is even or odd. If a number is divisible by 2, then it is an even number otherwise, it is odd. To verify a given number is even or odd in Java, we can use 3 different ways one with the modulus operator (%), another with the bitwise AND operator (&), and a third one using a switch statement. Example Scenarios: Let's understand the problem statement with some example scenarios: Input: number = 45 Output: result = odd ...
Read MoreHow can we convert a JSONArray to String Array in Java?
A JSONArray is a class provided by the org.json package that represents a collection of JSON values. These values can be of any type, such as strings, numbers, booleans, or even nested objects or arrays. If you do not know what JSON is, then you can read the JSON tutorial. Converting JSON Array to String ArrayWe can convert a JSONArray to String Array by using a simple loop as shown in the example below - import org.json.*; import java.util.*; public class JsonArraytoStringArrayTest { public static void main(String[] args) { ...
Read MoreHow to iterate List Using Streams in Java?
In Java, a List is an interface that stores a sequence of elements of similar type. Java provides various ways to iterate over a list, such as using a for loop, forEach loop, iterator object, stream, or forEach() method with a lambda expression. What is Stream in Java? In Java, a Stream is an interface, which represents a sequence of elements (or objects) supporting sequential and parallel aggregate operations. These operations can be used to produce the desired result. The Stream interface provides a method named stream(), which is used to create a sequential stream from the current collection (or ...
Read MoreHow can we convert a JSON array to a list using Jackson in Java?
Jackson is a Java-based library, and it can be useful for converting Java objects to JSON and JSON to Java objects. A Jackson API is faster than other API, needs less memory, and is good for large objects. We can convert a JSON array to a list using the ObjectMapper class. It has a useful method, readValue(), which takes a JSON string and converts it to the object class specified in the second argument. Before proceeding further, first of all, we need to import the Jackson library into our project. To do this, you can add the following dependency to ...
Read MoreHow do I get length of list of lists in Java?
In Java, a list is a collection that we use for storing elements. In many cases, we need to get the length of a list of lists. In this article, we will learn how to get the length of a list of lists in Java. List provides a method size() to get the count of elements present in the current list. To get the size of each list, we can iterate through each item in the list and add its size to get the count of all elements present in the list of lists. Ways to Get the Length of ...
Read MoreHow do you create a list with values in Java?
A List is a Collection in Java that is used for storing elements in sequence. In this article, we will be learning how to create a list with values in Java. Ways to Create a List with Values in Java There are various ways to create a list with values in Java. Below are the different approaches: Using Arrays.asList() method Using Stream.of() method Using List.of() method Using Arrays.asList() method The Arrays.asList() method returns the elements of the current array in the form of a List. This method ...
Read MoreCan we declare a constructor as private in Java?
Java constructor is a special method used to initialize objects. It has the same name as the class and is automatically called when an object is created. You can also declare a constructor as private to restrict object creation from outside the class. What is a Private Constructor? A private constructor is a constructor that is declared using the private access modifier. It restricts object creation from outside the class i.e., the class having a private constructor cannot be subclassed. Private constructors are used in design patterns like Singleton, or to prevent subclassing or instantiation. Purpose of a Private ...
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