Introduction

What you should already know

Getting Started with JAVA

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Java Entry Point

The entry point to the java function is the main function.

It is categorized by its (String[] args) as parameter to the function.

          
            // Class declaration
            public class MymainFunction {
                  // Java main function examples
                  public static void main(String[] args) {
                  }
            }
        
        
          

As you can see the main function is wrapped within a main class which is part of the object oriented structure of Java projects.

The name of the project is therefore "MyMainFuction"

Pointing to the Console

Welcome to the heart of Java programming – the console! This section is your gateway to mastering the command-line interface, where you'll wield the power of Java with finesse. Dive into the depths of Java development as you learn to navigate the console like a seasoned pro.

Embrace the command line as your playground for exploration and experimentation. From simple print statements to complex debugging sessions, the console is where Java developers thrive. Are you ready to embark on this journey? Let's point to the console and unleash the full potential of Java!

1. Introduction to Console Output: Begin your journey by understanding how Java communicates with the console.


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                // Basic console output
                public class HelloWorld {
                      public static void main(String[] args) {
                        System.out.println("Hello, world!"); // Display message on the console
                      }
                }
            
              



2. Print Statements Unleashed: Explore the power of print statements for direct console interaction.


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                // Using print and println statements to display messages
                public class PrintExample {
                      public static void main(String[] args) {
                        int number = 42;
                        System.out.print("The answer to life, the universe, and everything is: ");
                        System.out.println(number);
                      }
                }
            
            

Declaring Functions

In Java, you declare functions as methods within classes. Here's a basic example of how you can declare a function in Java:

          
            // Class declaration
            public class MyClass {
                  // Method declaration
                  public static void myFunction() {
                    // Method body
                    System.out.println("This is my function.");
                  }

                  // Main method (entry point of the program)
                  public static void main(String[] args) {
                    // Call the function
                    myFunction();
                  }
            }
        
        
          

In this example:

• We declare a class named 'MyClass'.
• Inside the class, we declare a method named 'myFunction()'. The public keyword indicates that the method can be accessed from outside the class. The static keyword means that the method belongs to the class itself rather than to instances of the class. The return type of the method is void, indicating that it does not return any value.
• Inside the method body, we have the code that defines the behavior of the function. In this case, it simply prints "This is my function." to the console.
• We also have a 'main()' method, which serves as the entry point of the program. Inside the main() method, we call the myFunction() method to execute its code.
• We also have a main() method, which serves as the entry point of the program. Inside the main() method, we call the myFunction() method to execute its code.

When you run the program, it will output:

         
 This is my function
        

Object Oriented Programming

Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data (attributes or properties) and code (methods or functions). Java is a prominent object-oriented programming language that fully supports OOP principles. Here are some key aspects of OOP in Java:

1. Classes and Objects: In Java, classes are blueprints for creating objects. A class defines the properties and behaviors (methods) that objects of that class will have. Objects are instances of classes.


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              public class MyClass {
                    // Method declaration
                    public static void myFunction() {
                      // Method body
                      System.out.println("This is my function.");
                    }

                    // Main method (entry point of the program)
                    public static void main(String[] args) {
                      // Call the function
                      myFunction();
                    }
              }
          
        



2. Encapsulation: Encapsulation is the bundling of data (attributes) and methods that operate on the data into a single unit (a class). Access to the data is typically restricted to methods of the class, ensuring data integrity and security.


3. Inheritance: Inheritance allows a class (subclass or child class) to inherit properties and methods from another class (superclass or parent class). This promotes code reuse and enables the creation of hierarchical class structures.


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              // Superclass
              class Animal {
                    void eat() {
                      System.out.println("Animal is eating.");
                    }
              }

              // Subclass
              class Dog extends Animal {
                    void bark() {
                      System.out.println("Dog is barking.");
                    }
              }
              Dog myDog = new Dog();
              myDog.eat(); // Inherited from Animal class
              myDog.bark();
           
         



4. Abstraction: Abstraction is the process of hiding the implementation details of a class and showing only the essential features to the user. Abstract classes and interfaces are used to achieve abstraction in Java.


5. Association, Aggregation, and Composition: These are forms of relationships between classes, where one class is related to another in some way. These relationships help in modeling complex systems and data structures.

Java's support for these OOP principles makes it a powerful language for building modular, maintainable, and scalable software applications. By leveraging OOP concepts effectively, developers can create robust and flexible solutions to meet a variety of requirements.