— Scott McNealy, Sun Microsystems Chairman, President and ceo

G.C.
Exercise Solutions

---

constructors and 
gc
you are here
4
271
Five-Minute Mystery Solution
Tom noticed that the constructor for the V2Radiator class took an 
ArrayList. That meant that every time the V3Radiator constructor was called, 
it passed an ArrayList in its super() call to the V2Radiator constructor. That 
meant that an extra five V2Radiator SimUnits were created. If Tom was right, 
total power use would have been 120, not the 100 that Sarahʼs expected ratios 
predicted.
Since all the Bot classes create SimUnits, writing a constructor for 
the SimUnit class, that printed out a line everytime a SimUnit was created, 
would have quickly highlighted the problem! 

---

---

this is a new chapter
273
10

numbers 
and 
statics
Numbers Matter
Make it Stick
Do the Math. 
But there’s more to working with numbers than just doing primitive 
arithmetic. You might want to get the absolute value of a number, or round a number, or find 
the larger of two numbers. You might want your numbers to print with exactly two decimal 
places, or you might want to put commas into your large numbers to make them easier to read. 
And what about working with dates? You might want to print dates in a variety of ways, or even 
manipulate dates to say things like, “add three weeks to today’s date”. And what about parsing 
a String into a number? Or turning a number into a String? You’re in luck. The Java API is full of 
handy number-tweaking methods ready and easy to use. But most of them are 
static
, so we’ll 
start by learning what it means for a variable or method to be static, including constants in 
Java—static final variables.

---