Chapter 4 Experiment 1 Describe tanks by class

Purpose:

                  Use classes to encapsulate the properties and behavior of objects

Tank.java

public class Tank {
       double speed;
       int bulletAmount;
	   void speedUp(int s){
		   speed=s+speed;
	   }
	   void speedDown(int d){
		   if(speed-d>=0)
		        speed=speed-d;
		   else
			   speed=0;
	   }
	   void setBulletAmount(int m){
		   bulletAmount=m;
	   }
	   int getBulletAmount(){
		   return bulletAmount;
	   }
	   double getSpeed(){
		   return speed;
	   }
       void fire(){
    	   if(bulletAmount>=1){
    		   bulletAmount=bulletAmount-1;
    		   System.out.println("Play a shell");
    	   }
    	   else{
    		   System.out.println("No more shells, can't fire!");
    	   }
       }
}

fight.java

public class Fight {
	public static void main(String[] args) {
		Tank tank1,tank2;
		tank1=new Tank();
		tank2=new Tank();
		tank1.setBulletAmount(10);
		tank2.setBulletAmount(10);
		System.out.println("The number of shells of tank1: "+tank1.getBulletAmount());
		System.out.println("The number of shells of tank2: "+tank2.getBulletAmount());
		tank1.speedUp(80);
		tank2.speedUp(80);
		System.out.println("The current speed of tank1: "+tank1.getSpeed());
		System.out.println("The current speed of tank2: "+tank2.getSpeed());
		tank1.speedDown(15);
		tank2.speedDown(30);
		System.out.println("The current speed of tank1: "+tank1.getSpeed());
		System.out.println("The current speed of tank2: "+tank2.getSpeed());
		System.out.println("tank1 fire: ");
		tank1.fire();
		System.out.println("tank2 fire: ");
		tank2.fire();
		tank2.fire();
		System.out.println("The number of shells of tank1: "+tank1.getBulletAmount());
		System.out.println("The number of shells of tank2: "+tank2.getBulletAmount());
	}

}

operation result: