Class_Till_Now(Final)

FinalOne

https://www.geeksforgeeks.org/java/classes-objects-java/

1)Classes and Objects:

• In Java, classes and objects are basic concepts of Object Oriented Programming (OOPs)
• A class itself does not occupy memory for its attributes and methods until an object is instantiated.
• used to represent real-world concepts and entities.
• A class is a template to create objects having similar properties a
• class is a blueprint for objects.
• An object is an instance of a class.

Example:
For example, the animal type Dog is a class, while a particular dog named Tommy is an object of the Dog class.

2)Methods:

• A method is a block of code designed to perform a specific task.
• They will execute only when we called.
• All methods in Java must belong to a class.
• Methods are similar to functions and expose the behavior of objects.

Types:
1.Predefined Methods (Built-in Methods)
2.User-defined Methods.

Syntax for the Methods:

1.Predefined Methods:

• Predefined methods are the method that is already defined in the Java class libraries.
• It is also known as the standard library method or built-in method.

For example, random() method which is present in the Math class and we can call it using the ClassName.methodName() as shown in the below example.

Example:
Math.random() // returns random value
Math.PI // return pi value

2.User defined Method:

• The method written by the user or programmer is known as a user-defined method.
• These methods are modified according to the requirement.

Example:
sayHello // user define method created above in the article
Greet()
setName()

Ref: https://www.geeksforgeeks.org/java/methods-in-java/

3)Different Ways to Create Java Method:
1.Instance Method.
2.Static Method.

1.Instance Method:

• Access the instance data using the object name.
• Declared inside a class. Example:

2.Static Method:

• Access the static data using class name.
• Declared inside class with static keyword. Example:

4)Typecasting:

• Typecasting is the process of converting one data type to another data type.

Types of Type Casting:

      1.Widening Type Casting
      2.Narrow Type Casting

1.Widening Type Casting:(Implicit)

• A lower data type is transformed into a higher one by a process known as widening type casting.
• Since there is no chance of data loss.
• Widening type casting is also sometimes called upcasting.

• It occurs.....

  1.The target type must be larger than the source type.
  2.Both data types must be compatible with each other.

2.Narrow Type Casting:(Explicit)

• The process of downsizing a bigger data type into a smaller one is known as narrowing type casting.
• It doesn't just happen by itself. If we don't explicitly do that, a compile-time error will occur.
• Narrowing type casting is unsafe because data loss might happen due to the lower data types.

5)Parameters:

• Parameters are variables defined in the method declaration after the method name inside parenthesis.
• You can pass values(Argument) to the method parameters, at the method call.
• Parameters are local variables which are assigned value of the arguments when the function is called