Method Overriding In Java - learngreen.net

 

Method overriding is a feature in object-oriented programming languages, that lets in a subclass to furnish a one-of-a-kind implementation of a method that is already described in its superclass.

In Java, when a subclass inherits a method from its superclass, it can redefine that approach with the equal name, return type, and parameters in the subclass. The overridden method in the subclass replaces the implementation of the approach inherited from the superclass.

When the overridden method is referred to as on an instance of the subclass, the subclass's implementation is performed as an alternative of the superclass's implementation.

This approves the subclass to customize the conduct of the method to suit its specific needs, while still maintaining the approach signature defined in the superclass.

Method overriding permits polymorphism, which ability that a variable of a superclass type can refer to an object of both the superclass or any of its subclasses, and the appropriate overridden technique will be invoked based totally on the actual type of the object.

Some necessary points to have in mind about method overriding in Java are:-

1. The method in the subclass must have the identical name, return type, and parameters as the method in the superclass.

2. The get admission to stage of the overridden method in the subclass can't be greater restrictive than the access level of the superclass method. It can be the equal or more permissive (e.g., a public method in the superclass can be overridden as public or protected in the subclass).

3. The overriding method in the subclass can use the @Override annotation to point out that it intends to override a method from the superclass. This annotation helps become aware of mistakes at compile-time if the approach signature does not in shape any approach in the superclass.

4. The super key-word can be used internal the subclass to explicitly call the overridden method from the superclass, permitting both implementations to be executed.

5. The final key-word can be used to prevent a method from being overridden. A remaining method in a superclass cannot be overridden by means of any subclass.

Method overriding lets in for flexibility and extensibility in object-oriented programming with the aid of enabling subclasses to grant their very own implementation of methods defined in their superclass. It promotes code reusability, modular design, and the implementation of particular conduct in subclasses while keeping a constant interface across the inheritance hierarchy.

 package Interview;
 public class MyClass {
 // Method in the superclass
 public void eat() {
 System.out.println("David eats mango ");
    }

 // Inner class extending the superclass
 public class Shyam extends MyClass {
 // Method overriding the superclass method
 @Override
 public void eat() {
 System.out.println("Mack eats grapes");
        }
    }
 public static void main(String[] args) {
 // Create an instance of the superclass
 MyClass obj = new MyClass();
 // Call the eat() method of the superclass
 obj.eat();
 /*
  *  Create an instance of the inner
  *  class using the outer class instance 
  */
 Shyam obj1 = obj.new Shyam();
 /*
  * Call the eat() method of the
  * inner class (overridden version) 
  */
 obj1.eat();
 // Output->
 // David eats mango 
 // Mack eats grapes
    }
}

 

Method Overloading In Java - learngreen.net

 Method overloading in Java lets in you to define a couple of methods in a class with the same title however different parameter lists. It helps you operate similar duties with one-of-a-kind types of inputs. When you call an overloaded method, Java determines which model of the method to execute based totally on the parameters you pass. This makes your code more flexible, readable, and avoids the need to come up with special names for similar operations.

 //Example1
 package Interview;
 
 public class MyClass {
 //Method to convert a String value to an int
 public int Change (String Value){
 return Integer.parseInt(Value);
	 }
 //Method that returns a double value as it is
 public double Change(double value){
 return value; 
 }
 public static void main (String[] args){
 // Create an object of MyClass	 
 MyClass obj = new MyClass();
 //Call the change method with string argument
 int num = obj.Change("58");
 //Call the change method with double argument
 double decimal = obj.Change(3.14);

 System.out.println(num);
 //Output-> 58
 System.out.println(decimal);
 //Output-> 3.14
	}
 }

 

//Example 2
package Interview;
 
 public class MyClass {
 //create method to divide integers	 
 public int divide (int r, int s) {
 return r/s;
 }
 //create method to divide doubles
 public double divide (double r, double s) {
 return r/s;	 
 }

 public static void main (String[] args){
 //create an object of MyClass	 
 MyClass obj = new MyClass();
 //call the divide method with integers &
 //store the result in division1
 int division1 = obj.divide(8, 2);
 System.out.println(division1);
 //output-> 4
 
 //call the divide method with doubles &
 //store the result in division2
 double division2 = obj.divide(5.5,2.5);
 System.out.println(division2);
 //output-> 2.2
	}
 }

 

 //Example 3

 package Interview;
 
 public class MyClass {
 public void print(String expression ) {
 //create method print with parameter string	
 System.out.println(expression);	 
 }
 public void print(int digit) {
 //create method print with parameter digit	 
 System.out.println(digit);
 }
 public void print(boolean flag) {
 //create method print with boolean parameter
 System.out.println(flag);
 }
 public static void main (String[] args){
 MyClass obj = new MyClass();
 obj.print("Save Water");
 //Output-> Save Water
 obj.print(84);
 //Output-> 84
 obj.print(true);
 //Output-> true
	}
 }

 

What is Inheritance In Java - learngreen.net

   In Java, inheritance is an essential concept that lets classes inherit residences and behaviors from different classes. It helps create a hierarchy of classes, the place a subclass can inherit matters from its superclass.

The superclass is the type we inherit from, and the subclass is the category that inherits from the superclass. The subclass can use the fields and techniques of the superclass, and additionally add its personal special ones.

To set up inheritance, we use the "extends" key-word in the category declaration.

The subclass can get right of entry to the superclass's stuff with the aid of the usage of the dot operator. It can additionally override techniques of the superclass to supply its personal implementation. This lets in us to personalize and specialize the conduct of our classes.

Inheritance helps us reuse code due to the fact we can outline frequent attributes and behaviors in the superclass and inherit them in more than one subclasses. It additionally allows polymorphism, which skill we can deal with objects of the subclass as objects of the superclass. This offers us flexibility and makes our code greater adaptable.

It's essential to be aware that Java helps single inheritance, which potential a category can solely inherit from one superclass. To work round this limitation, Java gives interfaces, which permit lessons to put in force a couple of interfaces to inherit conduct from extraordinary sources.

In summary, inheritance in Java lets us create classification hierarchies, reuse code, and make our code extra flexible. It's a effective device that helps us construct higher and extra geared up programs.

//Example 1-> Inheritance using Nested Class
 package Interview;
 public class MyClass {
 //create superclass with name "MyClass"
 public void hobby() {
 System.out.println("Playing Cricket");
	}
 public class NewClass extends MyClass {
 //Create Nested Class with name "NewClass"
 public void color() {
 System.out.println("The color is Red");
		}
	}
 public static void main (String[] args) {	
 MyClass obj = new MyClass();
 //Create object of superclass MyClass
 
 NewClass obj1 = obj.new NewClass();
 /*Create object of nested class
  * using object of superclass
  */
 obj.hobby();
 //Call the hobby method from the superclass
 obj1.color();
 //Call the color method from the Nested Class
	 }
  }
 
/*
 * output->
 * Playing cricket
 * The color is Red
 */

 

//Example 2-> Inheritance Method override

package Interview;
 public class MyClass {
 //Create superclass with name "MyClass"
 public void draw() {
 //Create draw() method
 System.out.println("Drawing a shape.");
	   }
 public class Circle extends MyClass {
 //Create Nested class Circle
 public void draw() {
 //Method Override
 System.out.println("Drawing a circle.");
	   }
 }
 public static void main (String[] args) {	
 MyClass obj = new MyClass();
 //Create object of MyClass
 Circle obj1 = obj.new Circle();
 /*
  * Create object of Nested Class
  * Circle using object of superclass
  * MyClass
  */
 obj.draw();
 // Call the draw method from MyClass
 obj1.draw();
 //Method Override for Nested Class
   }
}
 /*
  * Output->
  * Drawing a shape
  * Drawing a circle
 */

 

//Example 3->
// Inheritance with constructor

 package Interview;
 public class MyClass {
 //create superclass Name "MyClass"
 private String brand;
 //create String variable brand
 
 public MyClass(String brand) {
 this.brand = brand;
 //create constructor
 }
 public void displayBrand() {
	 System.out.println(brand);
 //create method displayBrand	 
 }
 
 public static class jeans extends MyClass {
 //create inner class jeans which inherit
//superclass
 public jeans(String brand) {
 super(brand);
 //constructor jeans inherit constructor from
 //superclass "MyClass"
	 }
 }
 public static void main (String[] args) {
 jeans obj = new jeans("Levis");
 //create object of jeans inner class
 obj.displayBrand();
 //called displayBrand method
	}
 }

 //Output-> Levis

 

How this Keyword works In Java - learngreen.net

 

In Java, the "this" keyword refers to the current object of a class. It is used to refer to a class’s contemporary instance variable. It can also additionally be used to call a function constructor of a class from any other constructor of the equal class.

Every object in Java has a reference to itself, which might also be retrieved with the "this" keyword. When you use "this" in a method, it refers to the class’s occasion variable, not the method’s neighborhood variable. This makes it effortless to distinguish between a class’s instance variables and local variables.

Advantages of Using this Keyword:-

Many a time, the parameter surpassed in the constructor have the same name as that of an instance variable already existing in the class. Here, the this key-word helps the programmer in averting the identify conflicts between the two.

The this keyword in Java helps the programmer in making the code greater readable and less complicated to apprehend specifically when working with complicated class hierarchies.

Using "this" to call any other constructor in the same classification can limit code duplication and improve code reusability.

Using "this" to refer to instance variables as a substitute of nearby variables can enhance encapsulation and forestall unintended modifications to the incorrect variable

To conclude, this keyword is a effective device in java for referencing to the modern-day object of a class. It is used to differentiate between a class’s instance variables and nearby variables, as properly as to call some other characteristic constructor of the same class. So, this is an essential keyword in Java programming as it helps in enhancing the code readability, reusability, and encapsulation.

 

 //Example 1
 package Interview;
 public class MyClass {
 public static String message ;
  
 public MyClass ( String message) {
 this.message = message;
  }
  
 public void printmessage() {
 System.out.println(this.message);
  }

 public static void main
 (String[] args) {	
 MyClass obj = new MyClass
 ("Welcome to India");
 obj.printmessage();
 // output-> Welcome
 // to India
	}
  }

 /*In this example we do
 *have a class "MyClass" with
 *a private instance variable
 *"message".Constructor
 *take message variable 
 *and assigns
 *it to instance variable 
 *using this keyword.
 *MyClass also has a 
 *method "printmessage"
 *which prints output using
 *this keyword.
 *In main method we do
 *create object of
 *MyClass and called the
 *"printmessage" method.
 */

 

 //Example 2
 package Interview;
 public class MyClass {
 int a;
 //Constructor with parameter
 public MyClass(int a) {
 //Using this keyword
 this.a=a;
 }
  
 public static void main
 (String[] args) {	
 MyClass obj = new MyClass(8);
 System.out.println (obj.a);
 //output-> 8
 
	  }
  }

 

//Example 3
 package Interview;
 public class MyClass {
 private String sentence;
 class nextClass {
 boolean isnextClass = true;
	}
 public  void setSentence() {
 MyClass.this.sentence = 
  "How are you?";
	}
 public static void main
 (String[] args) {	
 MyClass myObj = new MyClass();
 myObj.setSentence();
 System.out.println
 ("Sentence: " + myObj.sentence);
 // Output->
 // Sentence: How are you?
	  }
  }

 

What is Static keyword in Java - learngreen.net

        In Java, the static key-word is most frequently used to control memory. The "static" phrase in Java is used to make a variable or approach of a classification that can be shared among all objects of that class. Users can use set words with positive components of their pc programs. The static key-word is used with the classification and now not with a precise object of the class. The phrase "static" potential some thing that doesn't change and is used for matters that are the identical for every instance of a group. For example, a number that continually stays the same, or a way of doing things that every example follows.

In Java, "static" capability some thing that belongs to the classification rather of each object of the class. This is what you  understand about the word "static"

When a variable is labeled as "static" in a class, all objects of that class will use the equal value for it. This is additionally known as a team or class variable. All the things in the equal team share the same version of the factor being talked about. If one object adjustments a variable that doesn't change, it modifications for all objects.

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When you declare a method as "static" in your code, you can use it without having to create a whole class first. These approaches are related to the whole group, not just specific things. Static strategies can only use other static components and cannot use non-static components directly.

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A static block is a group of instructions that are surrounded by curly braces and start with the word "static." It is used to set up things that only need to occur once for a class, like getting starting values ready for variables that do not change. Static blocks only run one time when the class loads.

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In Java, you can declare a nested class as static. A static nested type is a class that is part of another class, but it can be created without needing the other type to be created first.

The word "static" helps us create things that are part of a type and can be used without simply making an object from that class. This is often used for things that are needed by different parts of a group.

Explain about Constructors In Java - learngreen.net

 Java constructors are a way to create things in our programs. A constructor is a special method that sets up objects in Java. The constructor is special method that happens when you make new from a class. It can be used to give starting values for things that belong to an object.

In Java, Constructor is like a set of instructions just like a method. This happens when you make a new example of the class. When the constructor is called, space for the object is reserved in the computer's memory. It is a way to start the object in a special way. Each time something is made with the "new()" word, something called a constructor is used.

// Constructor Code Example
package Interview;
public class MyClass { 

//Constructor

	MyClass() {
		System.out.println("Constructor Invoked");
	}
  public static void main(String[] args) {
       MyClass obj = new MyClass();
    }
 }

// Output-> Constructor Invoked

What is the difference between Constructors and Methods?

In Java constructors has the same name as the Class from which it belongs to but incase of methods its not important that methods must posses the same name as the class. Constructors and methods are different. Constructors don't give any information back, but methods do. Methods either give back specific information or nothing at all. Constructors are used only once when creating an object, while methods can be used many times.

Importance of Constructor In Java:-

Constructors set the starting values for the parts of an object. This makes sure that the thing starts off okay and stays that way. Constructors can take in information to set values for an object when it is made. This makes creating objects better suited to what your program needs. Constructors make new objects from a class. When you say 'new', the computer sets aside space and sets it up for the object to start working. Java allows you to create many constructors in a class with different types of information. This makes it possible to create things with different ways to start them off. If you don't make any constructors in a class with specific instructions, Java will automatically create a default constructor. This sets the object to its starting values. If you make a constructor in a class, the default constructor won't be there anymore. Constructors are important when one thing takes after another thing. When you make a new class out of an existing one, everything in the old class is copied before anything new is added. Constructors  make things that work for your program and do what it needs.

Calling of Constructor:- 

When we make something new using the word "new", at least one constructor (which could be the basic one) is used to give the initial values to the parts of what we made. There are some guidelines to follow when writing constructors. The name of a class and the name of its constructor must be the same. In Java, you can't make a constructor abstract, final, static, or Synchronized. Access modifiers in a constructor decide which other class can use the constructor. We've learned that constructors are used to set up an object's starting position. A constructor is like a group of instructions, just like how methods also have their own set of instructions. These are steps that happen when an object is made.

Types of constructor in Java:-

Default constructor

Parameterized Constructor

Copy Constructor

Default Constructor:-

A constructor without any information is called the default constructor. You do not see a default constructor because it is hidden. If we don't write a constructor that takes any information, the computer won't make one for us automatically. It is removed. It's getting too much work and people are using a certain kind of constructor. The way the object is created has been changed from the default to a new way where specific values can be given as inputs. The default constructor cannot be changed by the parameterized constructor.

package Interview;
public class MyClass {
	//Default Constructor
	MyClass() {
		System.out.println("Default Constructor");
	}
  public static void main(String[] args) {
       MyClass obj = new MyClass();
    }
 }

// Output-> Default Constructor

Parameterized Constructor:-

A parameterized constructor is a constructor that needs some information to be created. If we want to start using specific values for the class fields, we can use something called a parameterized constructor.

package Interview;
public class MyClass {
	String message;
	int number;
MyClass(String message, int number) {
		this.message = message;
		this.number = number;
	}
  public static void main(String[] args) {
       MyClass obj = new MyClass("Java", 8);
       System.out.println(obj.message + " " + obj.number);
    }
 }

// Output-> Java 8

Copy Constructor:-

The copy constructor is different from other constructors because it makes a new object by copying data from another object.

package Interview;
public class MyClass {
	private String color;
	private int number;
	
public MyClass (String color, int number) {
		this.color=color;
		this.number = number;
	}
	
	public MyClass(MyClass next) {
		this.color = next.color;
		this.number = next.number;
	}

  public static void main (String[] args) {	
	MyClass obj = new MyClass("Yellow", 85);
	MyClass obj1 = new MyClass(obj);
	System.out.println(obj.color + " " + obj.number);
	System.out.println(obj1.color + " "+ obj1.number);
   }

 }
// Output-> Yellow 85
//          Yellow 85

/* Within the output, able to see that both obj
 * and obj1 have the same values for their color
 * and number properties. This confirms that the
 * copy constructor successfully made a new object
 * obj1 with the same quality values as the initial
 * object obj.
 */

 

Methods In Java - learngreen.net

  In Java, methods are like mini-programs that do special jobs and can be used when you want them to. 

They gather similar code together into a package of instructions so it can be used again more easily. Below are few important things to remember about Java methods

Method Declaration:- To create a method, you need to give it a name, decide who can use it (public or private), what it will return (like numbers or words), and what input it needs (which may not be necessary).

Method Signature:- The method signature includes the method's name and the things it needs to work correctly. It helps you tell apart ways of doing things that have the same name, but use different information (called method overloading).

Return Type:- The return type tells what kind of information the method will give back when it finishes doing its job. When a method doesn't give any answer, it is called "void".

Parameters:- Methods can take some variables called parameters that help to pass data into the method. These parameters could be zero or more. "Parameters" means some values that are given to a function. They are written inside brackets and separated by commas.

Method Body:- The method body is a set of directions that are followed when the method is used. It's inside squiggly brackets { }.

Method Invocation:- To use a way of doing something, you have to give it a signal to start working. Method invocation means using the name of the method and putting parentheses after it. If the method needs information, you can put it inside the parentheses.

Method Overloading:-  Java lets you make different methods that have the same name but use different information. The computer program decides which action to take based on what we tell it to do when we give it information.

Recursion:- In Java, a method can call itself, called recursion. Recursion can help solve problems by breaking them down into smaller parts.

Method Accessibility:- Methods can be set to be accessible in different ways such as making them available to everyone (public), only to a certain class (private), to related classes (protected), or not specifying any accessibility (default). The access modifiers decide which methods can be seen and used by other classes.

Method Overriding:- Inheritance lets subclasses create their own way of using methods that come from the main class. This means doing things in a different way than what was planned before. The new way of doing things in the smaller group must have the identical title, parts, and outcome as the way of doing things in the larger group.

Types of methods in Java:-

//1. Method having no parameters and return value
  
      public void message( ) {
		System.out.println("Welcome on my blog");
	}

 /* This method doesn't return any results and 
 * it is declared as 'void'.
 * It prints "Welcome on my blog " when invoked.
 */ 

// 2. Method which has parameters and return value:-
  
    package Interview;
    public class MyClass {
	public int multiplyNumbers(int a,int b) {
	    int multiplication = a*b;
	    return multiplication;
	}
  public static void main(String[] args) {
  MyClass obj = new MyClass();
  int result=obj.multiplyNumbers(8,9);
  System.out.println(result);
    }
 }

// Output-> 72

 /* This code is about a class named MyClass.
  * Inside MyClass, there is a method called multiplyNumbers.
  * This method takes two numbers and multiplies them together.
  * It then return result . The main part of the program starts
  * by making a new MyClass object. Then it uses the multiplyNumbers
  * method with the numbers 8 and 9 as input.The answer is saved in
  * a variable "result" and then shown
  * on the screen using System.outprintln(result)
 */

 
  //3. Method with conditional statement
  
 public boolean isEven(int number) {
    if (number % 2 == 0) {
        return true;
    } else {
        return false;
    }
 }

 /* This method checks if the given number is even or not
  * by using a conditional statement. 
    It returns true if the number is even and false otherwise.
 */

 
 //4. Recursive Method
  
public int factorial(int n) {
    if (n == 0 || n == 1) {
        return 1;
    } else {
        return n * factorial(n - 1);
    }
 }

 /* This is an example of a recursive method
 *  that calculates the factorial of a number.
 *  It calls itself with a smaller value until
 *  the base case is reached (when n is 0 or 1).
 */

 
 // 5. Static Method
  
public static void printMessage(String message) {
    System.out.println(message);
 }

 /* This method is declared as static which
 *  means it doesnt require to create object.
 *  It can called directly.

These are different types of methods in Java and they explain how to use them. In Java programs, methods are very important for organizing the code, making it reusable and breaking it down into smaller parts.

Explain Objects & Classes in Java - learngreen.net

 In Java, we utilize objects and classes to compose code in a certain way called object-oriented programming. These are imperative thoughts to get it. They help show things in the real world and explain how they act and what they can do. Let me give you some quick explanations using some sample programs.

Classes:-

A class is like a plan for making things called objects. This describes how things of a certain type will act and what they can do. Classes are like plans or patterns that are used to make things called objects. They explain what something can do and how it looks if it belongs to a certain group. Classes group together information and actions that all belong to the same thing or idea. Classes help to sort and group information and activities about something. This explains what something is and what it's capable of doing. They help to arrange and separate code by gathering similar information and actions in one place. A class is a group of code that is given a name, made using the word "class," and includes different parts of the code inside it.

Objects:-

An object is like a thing created from a specific type of object. It's about one thing or object. We can make many things from one class. Things that we create in a program are called objects, and these objects are created based on a blueprint called a class. They each stand for unique things that fit into a particular group. Things have their own condition (values of characteristics) and actions (ways to do things).

You can make many things from one group. An object is something that belongs to a category. It is a thing defined by a group. Things are in their own condition and this depends on the qualities they have been given. They can show actions by using set ways in the group. We make things with the "new" word and the name of the group they belong to. Sometimes we add things inside the parentheses when we make them. Each thing has its own space to store information and can exist alone without needing anything else.

Code Examples:-

//Example 1
package Interview;
public class MyClass {
	
	int a = 4;  //Variable
	
  public static void main(String[] args) {
	  
  MyClass obj = new MyClass(); //Created Object
 System.out.println(obj.a);
	}
}

// Output-> 4

//Example 2
package Interview;
public class MyClass {
	
	String Name = "Shyam";  //Variable
	
  public static void main(String[] args) {
	  
  MyClass obj = new MyClass(); //Created Object
  System.out.println(obj.Name);
	}
 }

// Output-> Shyam

Important points:-

Classes make a plan for what an object should look like and how it should act. Things are made from categories and show one of a kind examples. Classes help to save and arrange code and information.

Things have their own special condition and can do stuff using methods. Java employments classes and objects to make computer programs that show real-world concepts. This makes the code modular and can be reused in several parts of the program. It too permits distinctive parts of the program to associated with each other.

How to use naming conventions in Java - learngreen.net

 Naming conventions play an vital role in Java programming as they assist make your code extra readable, understandable, and maintainable. By following steady naming conventions, you can make your code less difficult to comprehend now not only for yourself however also for other builders who may additionally work on your codebase. Let's delve deeper into the a range of factors of naming conventions in Java:-

1. Packages:-

Package names need to be all lowercase and observe a reverse area name notation. For example, if your area is "example.com" and you are creating a package deal for a precise project, it may want to be named as com.example.projectname.

It's advisable to use significant and descriptive bundle names that replicate the reason or functionality of the code contained within them.

2. Classes and Interfaces:-

Class and interface names ought to be written in CamelCase, starting with an uppercase letter.

Class names should be nouns or noun phrases that describe the entity or notion they represent. For example, Car, Employee, AccountManager.

Interface names ought to be adjectives, nouns, or noun phrases that describe the conduct or contract that imposing classes adhere to. For example, Serializable, Comparable, List.

3. Methods:-

Method names need to be written in camelCase, starting with a lowercase letter.

Use descriptive names that indicate the purpose or motion carried out by the method. The title ought to be a verb or a verb phrase that conveys the meant functionality. For example, calculateTotal(), getUserInput(), sendMessage().

4. Variables:-

Variable names have to be written in camelCase, beginning with a lowercase letter.

Use meaningful and descriptive names that indicate the motive or content material of the variable. Avoid single-letter variable names (except for loop counters) and pick out names that are self-explanatory. For example, firstName,   totalAmount,  customerList.

5. Constants:-

Constants, which are variables whose values do no longer change, must be written in uppercase letters with underscores keeping apart words.

Constants must have descriptive names that reflect their purpose. For example,  MAX_VALUE, DEFAULT_TIMEOUT,  PI.

6. Packages and modules:-

Package and module names should be in lowercase letters.

Separate phrases with dots (.) to indicate a hierarchy. For example,  com.example.mypackage, org.openai.myproject.

7. Boolean variables:-

Boolean variables need to be named as questions or statements that can be answered with true or false.

Use names that mirror the condition being represented. For example,  isAvailable,  hasPermission, isEnabled.

8. Acronyms and abbreviations:-

When using acronyms and abbreviations, deal with them as phrases in CamelCase format. This helps improve readability and avoids confusion.

For example,  XMLParser  as an alternative of  XmlParser,  HTTPRequest  rather of  HttpRequest.

9. Enumerations:-

Enumeration kinds should be written in uppercase letters with underscores separating words.

Enum names  be nouns or noun phrases that signify a series of related constants. For example, DayOfWeek,  Color,  Size.

It's important to be aware that whilst following these naming conventions is recommended, they are not strict rules. It's indispensable to prioritize consistency inside your codebase. If you are working on an present project, it is great to adhere to the conventions already set up by using the project's code. Additionally, if you are participating with other developers, make sure to observe any specific naming conventions or tips described with the aid of your team or organization.

By adhering to consistent naming conventions, you decorate the readability and maintainability of your Java code, making it simpler to understand, modify, and debug. 

Explain Object Oriented Programming Concepts In Java - learngreen.net

         A programming paradigm known as object-oriented programming (OOP) focuses on the idea of objects and how they interact to address challenging issues. The object-oriented programming language Java offers complete support for OOP ideas and principles. 

Let's dive deeper into Java OOP:-

1.Classes and Objects:- 

   Everything in Java revolves around classes and objects. A class is a blueprint or model that defines the structure and behavior of objects. It defines data (in the form of fields or variables) and  methods (functions) that can work with that data. An object, on the other hand, is an instance of a class. It represents a certain entity or concept in the program domain.  

2. Encapsulation:- Encapsulation is a basic OOP principle  that combines data and methods into a single unit called a class. This makes it possible to hide the internal implementation information of an object and expose only  necessary functions through well-defined interfaces. In Java, you can encapsulate using access modifiers (private, protected, public) to control the visibility of class members. By encapsulating data, you ensure data integrity and clearly separated implementation and use. 

3. Inheritance:-  One class can inherit traits and behaviours from another class through the mechanism of inheritance. The class from which it inherits is known as a superclass or base class, and the class from which it derives is known as a subclass or derived class. The Java language's "extends" keyword can be used to establish an inheritance connection. Inheritance promotes code reuse because subclasses can access and extend the functionality of the parent class. This allows you to model an "is-a" relationship where a subclass is a specialized version of a superclass. 

4. Polymorphism:-  Polymorphism means that it has many forms. Polymorphism in Java enables objects of various classes to be viewed as belonging to a single superclass. This makes the code expandable and adaptable. Static polymorphism and dynamic polymorphism are the two different types of polymorphism. Method overloading, which allows a class to have many methods with the same name but distinct parameters, achieves static polymorphism.

Dynamic polymorphism is achieved through method overriding, where a subclass provides a different implementation of a method  already defined in its superclass. Polymorphism is essential to writing flexible, reusable and maintainable code. 

5. Abstraction:-  Abstraction focuses on providing a simplified and meaningful representation of an object. It identifies the important properties and behavior of an object and ignores unnecessary details. In Java, abstraction can be achieved through abstract classes and interfaces. An abstract class is a class that cannot be instantiated and provides a partial implementation of the class hierarchy. It acts as a blueprint for subclasses to implement certain behaviors. On the other hand, an interface is a contract that defines a set of methods that a class must implement. This allows for multiple inheritance and provides the ability to achieve full abstraction.  

6. Binding, Joining and Composition:- In addition to the basic concepts of OOP, Java also supports various types of relationships between classes. A union represents a relationship in which objects of two classes are related, but does not involve ownership or security. Aggregation represents a relationship where one class is a part or component of another class, but the parts can exist independently. A composite represents a stronger association where the parts are exclusive to the whole and cannot exist independently.  

7. Design Patterns:- Java is often used in conjunction with design patterns, which are proven solutions to common software design problems. Design patterns provide reusable templates for designing  modular, maintainable, and extensible code. Some of the more commonly used design patterns in Java are Singleton, Factory, Observer, Adapter, and Strategy.

Using principles You can create well-structured, modular, and scalable programmes using Java's OOP ideas. Because OOP encourages code reuse, maintainability, and flexibility, it's a useful paradigm for creating intricate software systems.

Questions & Answers:-

1.What is Object Oriented Programming (OOP)?

Object-oriented programming is a programming paradigm that organizes code into objects that encapsulate statistics and behavior.

2. What are the four main standards of oops?

The four important concepts of oops are encapsulation, inheritance, polymorphism and abstraction.

3. What is encapsulation?

Encapsulation skill condensing statistics and techniques into a single class, hiding  interior details and providing a public interface for communication.

4. What is inheritance?

Inheritance is a mechanism in Java the place a type inherits the properties and techniques of another class, enabling code reuse and creating hierarchical relationships.

5. What is polymorphism?

Polymorphism is the capability of an object to take  distinctive types or behave otherwise depending on the context. This lets in objects belonging to one-of-a-kind classes to be dealt with as objects of a common superclass.

6. What is abstraction?

Abstraction is the technique of simplifying complicated structures through focusing on important facets and hiding unnecessary details.

7. What is a class?  

A category is a blueprint or model for creating objects. It defines the homes and conduct of the objects of the class.

8 What is an object?

An object is an occasion of a classification that encapsulates the data and conduct defined through the class.

9.What is a constructor?

A constructor is a exclusive approach in a classification that is used to initialize objects. It is mechanically referred to as  when the object is created.

  

10. What is the difference between a type and an object?

A class is a blueprint or template for creating objects, while an object is an instance of a class.

11. What is a method?

A technique is a set of commands or behaviors related with an object or  class. It defines the operations that objects of the classification can perform.

12. What does approach overloading mean?

Method overloading is a Java feature  that lets in a category to have a couple of techniques with the identical title but distinctive parameters.

13.What is method override?

Method override is a Java characteristic  that permits a subclass to grant a exclusive implementation of a method  already defined in its superclass.

14. What is this keyword used for in Java?

The Java key-word "this" refers to the present day occasion of the class. It is used to refer to  occasion variables or strategies of the modern-day object.

15. What is the distinction between an instance variable and a classification variable?

An instance variable is a variable that belongs to a precise occasion of a class, whilst a classification variable is a variable that belongs to the classification itself and is shared between all cases of the class. 

 

16 What is the "super" keyword used for in Java?

In Java, the keyword "super" is used to refer to the superclass of a class. It is used to name the superclass constructor, accessor methods or superclass variables and to distinguish superclass methods.

17.Which method is hidden in Java?

Method hiding takes place when a subclass defines a static method that has the identical signature as a static method in its superclass. A subclass approach hides a superclass technique alternatively of overriding it.

18. What is the difference between composition and sequence?

Inheritance creates an "is-a" relationship between classes, where a subclass inherits homes and methods from its superclass. Composition creates a "has-" relationship through combining objects of unique instructions to shape a new class.

19. What is the Java key-word 'final' used for?

The ultimate key-word in Java is used to avert enhancing classes, strategies and variables. A closing class can't be subclassed, a closing method can't be overridden, and a last variable cannot be overridden.

20. What is an abstract category in Java?

An abstract type is a type that can't be instantiated however can be subclassed. It can comprise abstract strategies that are intended to be overridden by means of  subclasses.

21. What is Java User Interface?

A Java interface  is a collection of abstract methods. It defines the contract that classes must observe when enforcing a union. A single class can put in force a couple of interfaces.

22. What is the difference between an summary class and an interface?

An abstract category can include each summary and non-abstract methods, while an interface can include solely  abstract methods. A class can put in force a couple of interfaces, but it can only inherit from  one class.

23.What is technique overloading?

Method overloading is a Java characteristic  that permits a type to have more than one strategies with the equal title but unique parameters.

24. What is method override?

Method override is a Java feature  that allows a subclass to supply a special implementation of a method  already defined in its superclass.

25. What is the difference between checked and unchecked exceptions in Java?

Checked exceptions are checked at the compilation stage and must be mentioned or handled, whilst unchecked exceptions are now not checked at the compilation stage and  require no distinctive handling.

26. What is the "instanceof" operator used for in Java?

In Java, the "instanceof" operator  is used to check whether or not an object is an occasion of a certain classification or implements a certain interface. It returns proper or false based on the result.

27. What is the reason of static key-word in Java?

In Java, variables, strategies and nested lessons that belong to the class itself as an alternative than to instances of the type are used to declare the "static" keyword. Static individuals can be used except creating an object.

What are comments in Java - learngreen.net

 Comments are lines of Java code that are ignored by the compiler and are intended to help human readers better comprehend the code. They explain the purpose, functionality, and specifics of the implementation of the code. Comments have no effect on the program's behavior at runtime because they are not executed as part of it.

There are three kinds of remarks in Java:-

1.One-sentence remarks:- These remarks start with two forward cuts (//) and go on for the rest of the line. Typically, single-line comments are used within the code for brief explanations or clarifications.

// Comment 2 is a single line. Comments that span multiple lines:- 

These comments end with an asterisk followed by a forward slash (*/) and begin with a forward slash. Multi-line remarks can traverse various lines and are valuable for giving itemized portrayals or remarking out blocks of code.

* This is a comment with multiple lines. It can traverse different lines.

*/

3.Notes on the documentation:- These comments, which are also known as Javadoc comments, can be used to document classes, interfaces, methods, and fields. They end with a reference bullet followed by a forward cut (*/) and start with a forward cut followed by two marks (/**). The purpose, usage, parameters, return values, and exceptions of the documented code elements are all described in the documentation comments.

/** * This is a comment for a class, interface, method, or field in the documentation.

 */ Tools like Javadoc, which can generate HTML documentation from code comments, process documentation comments. They are normally used to give Programming interface documentation and assist different designers with understanding how to utilize the code.

Readability, maintainability, and collaboration all depend on comments. They make it easier for others, including potential code maintainers, to comprehend the codebase, provide context for the code, and enable developers to explain their thinking process. In software development, it is considered good practice to write comments that are clear and meaningful.

Code description:- Comments are used to explain the purpose or function of a particular line of code. They provide insight into the logic and rationale of your implementation, making it easier for other developers (including yourself) to understand your code.

2.Temporarily remove code:- Comments are often used to temporarily disable or comment out sections of code that are not currently needed. This is useful during development to test alternative solutions or fix issues without removing code entirely.

3.TODO & NOTES:- Comments help you leave reminders, notes or "TODO" tasks for yourself and other developers. These comments highlight areas that need attention or improvement in the future. Helps track unfinished work or areas that need further investigation. 

4.Version control and collaboration:- Comments can be used to communicate changes made to the code base. If you use a version control system like Git, you can annotate commit messages to provide a summary of the changes made. This facilitates collaboration and helps team members understand the purpose and context of code changes.

5.Prevent execution:- You can prevent execution by placing a comment before a line or block of code. This is useful for debugging purposes or to temporarily exclude certain pieces of code that might be causing problems.

6.Organize your code:- You can use comments to structure and organize your code into logical sections. Comments add section headings and divide code into meaningful blocks to make your code base easier to navigate and understand. 

7.Inline comments:- Comments can also be placed next to specific lines of code to provide additional explanation or clarification. These comments are useful when the code itself is not self-explanatory and requires additional context.

Remember that comments are valuable, but writing clean, understandable code is just as important. Comments should complement the code, not replace it. Well-written code with meaningful variable names, clear function definitions, and good formatting can reduce the need for excessive comments. However, judicious use of comments can greatly improve the readability and maintainability of Java code.