java classes

                                    // this might help you understand how classes work
public class MathTest {

    public static void main(String[] args) {

        class MathAdd {

            int num1;
            int num2;

            public int addNumbers() {

                int addThemUp = num1 + num2;
                return addThemUp;
            }
        }

        MathAdd addition = new MathAdd(); // create a new instance of the class

        // you can access variables from the class 
        addition.num1 = 10; 
        addition.num2 = 20;

        // and use the method from the class to add them up
        System.out.println(addition.addNumbers());

    }
}

                                    double floor = Math.floor(7.343);  // floor = 7.0
//rounds to the value down to the nearest integer value (returned as double)

                                    public class Bicycle {
        
    // the Bicycle class has
    // three fields
    public int cadence;
    public int gear;
    public int speed;
        
    // the Bicycle class has
    // one constructor
    public Bicycle(int startCadence, int startSpeed, int startGear) {
        gear = startGear;
        cadence = startCadence;
        speed = startSpeed;
    }
        
    // the Bicycle class has
    // four methods
    public void setCadence(int newValue) {
        cadence = newValue;
    }
        
    public void setGear(int newValue) {
        gear = newValue;
    }
        
    public void applyBrake(int decrement) {
        speed -= decrement;
    }
        
    public void speedUp(int increment) {
        speed += increment;
    }
        
}

                                    public class Main {
 public static void main (String[] args) {
	System.out.println("Hello World");
 } 
}

                                    Class is a blueprint or template which
you can create as many objects as you 
like. Object is a member or instance
of a class.
Class is declared using class keyword,
Object is created through
new keyword mainly. A class is a template
  for objects. A class defines 
object properties including a valid range
    of values, and a default value. 
A class also describes object behavior.