Hope my earlier explanation about object is understood to everyone.
Now, i am going to discuss next about classes.
let us take e.g. from real world i.e. Car. here, car has many types but kind is same.All of the same make and model.
Each Car is made of same prototype or blueprint and therefore, contains same components.
In OOPS, we can say car is an instance of the class of the objects knows as"CARS".
so, class is the prototype from which individual objects are created. 
I repeat my earlier e.g. over here i.e. class car which i posted in earlier post.
i just want to explain that the field cadence, speed, gear , music system volume all represents the state & the method change cadence, change gear, change speed, change volume defines its interaction from outside world.
Here, you may noticed that car doesn't contain a main method, that is because it just a prototype not a complete application.
In next post i will explain this prototype with e.g.

  1. Yes, class is a blueprint for objects.


    More general we can say that a class is a group of objects which have similar behavior and characteristics.
    Abstract Explanation:
    For e.g. as in Schools classes are there which categories the syllabus for students accordingly. In 1st Class All the students have same thing to study ABCD
    While all 5th class student have comman syllabus to study Arithmetic operations
    While all 10 class student have same syallbus to study Calculus.

    i.e. people with common properties and characteristics are grouped in Classes 

    Real world Explanation:
    Suppose you  what to buy a Car, when u think about car you think in a abstract way you think about the functions and conman structure which provided by car\
    But when u think about specific Car : Black BMW, Red Color Audi or any other model of your choice, these are real entities not abstract

    i.e Car is class and BMW and Audi are the different objects of the Car class



    Hope these explanations help you sink the concepts of classes in Java

    Your going good, Keep on learning and posting new stuffs and thoughts!!

  1. now , here i explained class with e.g.,

    class car {
    public static void main (string[]arg)
    {
    car objects
    car Mercedes = new Car();
    car BMW = new Car();
    now, interact behavior on state i.e. invoke methods on object
    car1.changeCadence(50);
    car1.changeGear(2);
    car1.changeSpeedup(10);
    car1.changeMusicvolume(15);
    car1.printStates();

    car2.changeCadence(40);
    car2.changeGear(3);
    car2.changeSpeedup(20);
    car2.changeMusicvolume(18);
    car2.printStates();
    }
    }


    o/p will be;
    cadence=50, gear=2; speedup= 10; music volume=15
    cadence=40; gear=3; speedup= 20; music volume=18

  1. First of all instead of car1 and car2 you need to use Mercedes and BMW(the objects you have created) to access class members using dot operator.

    First create a class Car consists of its properties and methods and then create a Test class to create car objects and test the methods there.

    Car Class:

    public class Car{
    //state or field declarations
    double cadence
    double speed
    int gear
    int musicSystemVolume
    //Constructor
    Car()
    //method Declarations
    public void changeCadence(double cadence){
     this.cadence = cadence
    };
    public void changeSpeed(double speed){
     this.speed = speed
    };
    public voidchangeGear(int gear){
     this.gear = gear
    };
     public voidchangeVolume(int musicSystemVolume){
     this.musicSystemVolume = musicSystemVolume
    };
    public void printStates(){
    System.out.print("cardence="+ this.cadence +", ");
    System.out.print("gear="+ this.gear +", ");
    System.out.print("speedup="+ this.speed +", ");
    System.out.print("music volume="+ this.musicSystemVolume);
    }
    //End of class
    }

    CarTest Class:
     
    public class CarTest{
    public static void main(String args[]){
    //create objects of car class 
    Car BMW = new Car();
    Car Mercedes = new Car();
    // interact behavior on state i.e. invoke methods on object
    BMW.changeCadence(50);
    BMW.changeGear(2);
    BMW.changeSpeedup(10);
    BMW.changeMusicvolume(15);
    BMW.printStates();
    Mercedes.changeCadence(40);
    Mercedes.changeGear(3);
    Mercedes.changeSpeedup(20);
    Mercedes.changeMusicvolume(18);
    Mercedes.printStates();
    }
    //End of class
    }

    o/p will be;
    cadence=50, gear=2; speedup= 10; music volume=15
    cadence=40; gear=3; speedup= 20; music volume=18
     

    Ankita  try to learn and follow the correct assumptions and standards provided by OOPS
    All the best !!

  1. http://www.mindstick.com/blog/10869/Object%20and%20class%20in%20java#.VUKL09JViko

  1. I struct in making program on class student.

    problem is that there are many states i.e. color, name, age, class, gender
    behavior i.e. writing, reading, listening, hearing, speaking.
    so, i want to ask how to assign local variable for such state which interact with outside world.
    If we assume that student is normal then, its behavior got change, then it is easy to make program.
    please, suggest in comment with suitable ans.

  1. Ankita can you provide me your code, then i can implement your issue and explain you

  1. can you share your code , i want to see how you implement local variable for this prob.

  1. Ankita i wouldn't understand you problem, but local variables are local to methods only you can't access them outside the method. However, your can access instance variables the better way is to make them private and provide getter- setter methods to access them.

    As per Student class implementation here is a simple sample for your learning:

    Student Class:

    public Class Student{
    //state or field decelerations
    String color
    String name;
    int age;
    int studentClass
    char gender;

    //constructor
    Student(String color,String name,int age,int studentClass,char gender){
    this.color = color;
    this.name = name;
    this.age = age;
    this.studentClass = studentClass;
    this.gender = gender;
    }

    //method implementations
    public void writing(String expression){
    System.out.println( this.name + "is writing " + expression);
    }

    public void reading(String expression){
    System.out.println( this.name + "is reading " + expression);
    }

    public void listening(String music){
    System.out.println( this.name + "is listening " + music);
    }

    public void hearing(String expression){
    System.out.println( this.name + "is hearing " + expression);
    }

    public void speaking(String expression){
    System.out.println( this.name + "is speaking " + expression);
    }

    //End of the class
    }

    StudentTest Class:

    public class StudentTest{

    public static void main(String[] args){

    //Create objects
    Student ravi = new Student("White", "Ravi", 22, 12, 'M');
    Student swati = new Student("Black", "Swati", 18, 10, 'F');

    //Acess methods and instance variable using Student object
    ravi.writing("Stories");
    ravi.reading("Newspapaer");
    ravi.listening("Pop");
    System.out.println(ravi. name + " is  " + ravi.age + "  years old and studies in "+ ravi.studentClass +" class " );

    swati.writing("Poems");
    swati.reading("English");
    swati.listening("Rock");
    System.out.println(swati. name + " is  " + swati.age + " old and studies in " + swati.studentClass + " class " );
    }

    //End of class
    }

    O/P:

    Ravi is writing Stories
    Ravi is reading Newspapaer
    Ravi is listening Pop
    Ravi is 22 years old and studies in 12 class
    Swati is writing Poems
    Swati is reading English
    Swati is listening Rock
    Swati is 18 years old and studies in 10 class


    Hope this will help you understand classes and communication between object and class members!!

  1. by this way i already done, anyways thanks, but i want to know is there any case if he/she is abnormal then what we will do? is it possible to make such programs? 

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