1. Classes One class usually represents one type of object
May contain its own member variables
May contain its own methods to operate on the member variables
Usually one class is defined in one Java file
In the entire program exactly one class should contain a main method

2. Vehicle class /* A program that uses the Vehicle class.
Call this file VehicleDemo.java */
class Vehicle {
int passengers; // number of passengers
int fuelCapacity; // fuel capacity in litres
int kmperlitre; // fuel consumption in kilometer per litre }

3. // This class declares an object of type Vehicle. class VehicleDemo {
Contd.
// This class declares an object of type Vehicle.
class VehicleDemo {
public static void main(String args[]) {
Vehicle minivan = new Vehicle();
double range;
// assign values to fields in minivan
minivan.passengers = 7;
minivan.fuelCapacity = 16;
minivan.kmperliter = 21;
// compute the range assuming a full tank of gas
range = minivan.fuelCapacity * minivan.kmperliter;
System.out.println("Minivan can carry " + minivan.passengers +
" with a range of " + range+" kms"); }

4. Contd. // This program creates two Vehicle objects. class Vehicle {
int passengers; // number of passengers
double fuelCapacity; // fuel capacity
double kmperliter; // fuel consumption }
// This class declares an object of type Vehicle.
class TwoVehicles {
public static void main(String args[]) {
Vehicle minivan = new Vehicle();
Vehicle sportscar = new Vehicle();
double range1, range2;
// assign values to fields in minivan
minivan.passengers = 7;
minivan.fuelCapacity = 16;
minivan.kmperliter = 21;
// assign values to fields in sportscar
sportscar.passengers = 2;
sportscar.fuelCapacity = 14;
sportscar.kmperliter = 12;
// compute the ranges assuming a full tank of gas
range1 = minivan.fuelCapacity * minivan.kmperliter;
range2 = sportscar.fuelCapacity * sportscar.kmperliter;
System.out.println("Minivan can carry " + minivan.passengers +
" with a range of " + range1);
System.out.println("Sportscar can carry " + sportscar.passengers +
" with a range of " + range2);

5. Add method // Add range to Vehicle. class Vehicle {
int passengers; // number of passengers
double FuelCapacity; // fuel capacity
double kmperliter; // fuel consumption
// Display the range.
void range() {
System.out.println("Range is " + FuelCapacity * kmperliter); }
class AddMeth {
public static void main(String args[]) {
Vehicle minivan = new Vehicle();
Vehicle sportscar = new Vehicle();
// assign values to fields in minivan
minivan.passengers = 7;
minivan.FuelCapacity = 16;
minivan.kmperliter = 21;
// assign values to fields in sportscar
sportscar.passengers = 2;
sportscar.FuelCapacity = 14;
sportscar.kmperliter = 12;
System.out.print("Minivan can carry " + minivan.passengers + ". ");
minivan.range(); // display range of minivan
System.out.print("Sportscar can carry " + sportscar.passengers + ". ");
sportscar.range(); // display range of sportscar.