What is Class & Objects In JAVA || Class and Objects in oops

Classes and Objects In Java

📝What is 'Class' in Java? :

• A Class is a Logical entity or Blueprint using which we can create multiple Objects. 
• We cannot create an Object without a Class. Hence Step.1 create a class and then create any number of objects. 
• Multiple Objects created using the same class are called as Similar Object or Identical Object. 
• Every Object work independently, I.e.., if one Object is modified or destroyed then it does not affect another Object. 

📝What is 'Object' in java? : 

• An object is a Real-world Physical entity. 
• Anything which has Physical presence or Physical appearance can be considered as an Object.

🌟Object Contains two Important things Or Properties:-

1. States
2. Behavior

• After successful compilation, the compiler generates default Constructor. Where the constructor name must be the same as a class name. 

Example: 

🎖Some Important Points Of Object:-

• In java, Objects are stored in Heap Memory. Memory allocation & Memory deallocation i.e, complete Memory management is taken care by JVM. 
• Jvm creates an object in heap Memory when we call the Constructor using a "new" Keyword. 
• Object address is represented in Hexa Decimal format. 
• The Class name and object name must be the same.
• This address is started in a variable called a reference variable, which helps in accessing the data present in the Object.

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🎖How To Create Object in java, and how it's Stored In Memory:-

Example(1):   

Example(2):   

🌟Object Reference / Object Address : 

• A Reference is the one which stores an Object address, Hence Object Reference is present in Heap Memory. 

Example: 

🌟what Are the States of an object: 

• The State of an object is nothing but the property/information or data which describes an Object.
• The data member is nothing but a data holder, which holds / stores the data. 

 States:- It is always representing features of an Object.

Behavior:- It always represents the Action performed by an Object.

📎There are 2 types of Data Member: 
➢ Variable.
➢ Constant.

• In the case of Variable, the data Varies I.e.., the data Changes. 
• Programmatically non-final data members are called Variable. 
• Constant is the data member which represents Fixed Value. 
• Programmatically we declare Constant using Final Keyword.

Example: 

final name = “Dog” ;  →  Constant. 

name = “ Tommy” ;  → Variable. 

Since an Object is derived from a class, the States & Behaviors of an Object must be first declared in class, Hence States & Behaviors are contents of the class. 

Example:  

➢Object Creation & Direct Initialization:

➢Object Creation & Initialization using Object Reference 

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