Classes Review

Gnome

A Gnome has a double precision height in meters and an integer weight in kilograms. When you make a new Gnome, if you do not specify the weight it is assumed to be 10kg.

    Gnome a = new Gnome(0.37, 4); // 0.37m, 4kg
    Gnome b = new Gnome(0.61); // 0.61m, 10kg

The Gnome class should have the following methods:

1. public void grow(): Increase the height by 0.1m.
2. public void eat(): A Gnome gains 1kg every 3 times it eats.
3. public String see(): Returns a string showing height and weight: “ht: 0.37m, wt: 4kg” for the Gnome a above.

• Write the complete Gnome class.
• Demonstrate its use by making a 12kg, 80cm tall gnome, having it grow and then eat 5 times. Print out what you see(): it should be 0.9m and 13kg.
  

ShootingStar

[This class had problems, was unclear and the details of tick() are not important now.]

The universe schedules shooting stars to appear at a certain time. A shooting star has an appearTime (double) and a brightness (int), both of which are set in the constructor.

The current time in “ticks” when a shooting star is constructed is always 0. A shooting star will keep track of time on its own (when tick() is called, time passes).

The constructor you must support is:

 // a star that appears at time 3.7 with brightness 8
 ShootingStar c = new ShootingStar(3.7, 8); 

The methods you need are:

1. public void tick(): Called by the universe to increase the current time by one. Do not call this in your code.
2. public void explode(): Makes brightness = 1000 for the next 6 ticks, then brightness becomes 0.
3. public int getBrightness(): Return the brightness for the current time (as the shooting star knows). The reported brightness is zero before the star appears.

How should it work?

 ShootingStar c = new ShootingStar(3.7, 8);
 for(int t=0; t<12; t++) {
     System.out.println(t+" shows "+c.getBrightness());
     c.tick();
     if (t==4) c.explode();
 }

Code above gives the output:

 0 shows 0
 1 shows 0
 2 shows 0
 3 shows 0
 4 shows 8
 5 shows 1000
 6 shows 1000
 7 shows 1000
 8 shows 1000
 9 shows 1000
10 shows 1000
11 shows 0
12 shows 0