class Test{ /* 1. Properties/Variables/Fields 2. Methods 3. Constrcutors 4. Blocks 1. Properties/Variables/Fields --------------------------------- Two types of Properties -> instance Properties -> static properties instance Properties ---------------------- -> Values of instance properties are available only to a specified object static properties ------------------ -> Values of static properties are available to all the obejcts. -> static data can be accessed directly with out help of object -> If The static data is defined in another class, then data can be accessed with class name 2. Methods ----------- Two Types -> instance methods -> non static method allows instance and static data -> instance methods must be called with a object, if you are calling from a static method -> static methods -> static methods allows static data directly -> static methods never allow instance data directly Q1: Why I need object? -> To access non static data from a static method in the same class -> To access non static data from a non static method in the different class */ int x=1000; // instance variable static int y=2000; // static variable void f1(){ // non static -> instance x=877; y=7777; } static void f2(){ // static method Test obj=new Test(); y=77772; obj.x=7777; obj.f1(); // valid } public static void main(String[] abc){ //System.out.println("--- hello world"); Test t1= new Test(); Test t2= new Test(); System.out.println(y); System.out.println(t1.x); } }