Author: alegru

type variableName = variableValue; public class Car { String brand; int maxSpeed; } class Car { String brand; int maxSpeed; public void printFields() { System.out.println(“BRAND: ” + brand); System.out.println(“MAX SPEED: ” + maxSpeed); } } public class Test { public static void main(String[] args) { Car ford = new Car(); ford.brand = “Ford”; ford.maxSpeed =…

Read More Variable in Java

class Car { int numberOfSeats = 4; void addOneSeat(int numberOfSeats) { numberOfSeats = numberOfSeats + 1; // changes will only affect the local variable } public static void main(String args[]) { Car car = new Car(); System.out.println(“Number of seats before the change: ” + car.numberOfSeats); car.addOneSeat(car.numberOfSeats); System.out.println(“Number of seats after the change ” + car.numberOfSeats);…

Read More Java Pass-by-Value vs Pass-by-Reference

In addition to the Java Runtime Environment (JRE), the JDK includes the following components: Compiler The Java compiler is used to convert Java source code into bytecode that can be executed on the Java Virtual Machine (JVM). A compiler is a command-line tool that takes a .java file as input and produces a .class file…

Read More JRE, JDK, and JVM: Understanding Differences and Uses

byte Uses 1 byte (8 bits) for a binary record of integers Values ​​of this type are integers in the range -2 ^ 7 to 2 ^ 7-1, ie. [-128, 127] The default value is 0 Example: byte var1=120, byte var2=-30 short Uses 2 bytes (16 bits) to write integer binaries Values ​​of this type…

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Operator Description Example + Indicates positive value +a – Negates an expression value (Converts positive number to negative) -a ++ Increments a value by 1 ++a — Decrements a value by 1 –a ! Inverts the value of a boolean type !true gives false %= Assigns the remainder to the left operand when dividing the…

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Java is a programming language that is widely known for its versatility, power, and many features. It is popular among developers due to its object-oriented design, portability, and strong security. Java’s object-oriented design allows developers to organize their code into modular units, making it easier to build large-scale applications. Java’s portability means that code can…

Read More Java’s Powerful Features: A Comprehensive Guide

public class App { public static void main(String[] args) { // … } } public class App { public static void main(String[] args) { for(String s : args) { System.out.println(s); } } } public static void main(String[] args) public static void main(String []args)  public static void main(String args[]) public static void main(String… args) static public void main(String[] args) public static final void main(String[] args) final public static void main(String[] args)

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class Vehicle { int maxSpeed = 250; public void printMaxSpeed() { System.out.println(“Max speed: ” + maxSpeed); } } class Car extends Vehicle { int maxSpeed = 300; @Override public void printMaxSpeed() { System.out.println(“Max speed: ” + maxSpeed); } } class Test { public static void main(String[] args) { Vehicle vehicle = new Car(); // upcasting…

Read More Upcasting Vs Downcasting in Java

{ “firstName” : “John”, “lastName”: “Doe”, “gender”: “Male”, “state”: “Texas” } public class Person { private String firstName; private String lastName; private String state; // constructors, getters and setters } public class Person { private String firstName; private String lastName; private String gender; <<<< private String state; } import com.fasterxml.jackson.annotation.JsonIgnoreProperties; @JsonIgnoreProperties(ignoreUnknown = true) public class…

Read More Unrecognized field not marked as ignorable – Java Jackson

{ “firstName”:”John”, “lastName”:”Doe”, “username”:”johnDoe#1″, “membershipType”:”Platinum”, “address”: { “street”:”5th Avenue”, “city”:”New York”, “state”:”New York” } } import lombok.*; @Data @NoArgsConstructor @AllArgsConstructor public class Customer { private String firstName; private String lastName; private String membershipType; private Address address; } @Data @NoArgsConstructor @AllArgsConstructor public class Address { private String street; private String city; private String state; } import…

Read More @JsonIgnore Annotation in Java