June 22, 2011

ArrayList
- a generic class, should be restricted for use
Array List tmpCards = new ArrayList ()
.
.
.
tmpCards.add(anotherCard);
.
.
.
Card[] allCards = new Card[tmpCards.size()]
allCards= tmpCards.toArray(allCards);


How to check if Equal?

String s1 = "abc"
String s2 = "abc"

'==' tests equality of reference

if (s1 == s2) or s1.equals(s2)
System.out.println ("equal")
else
System.out.println("not equal")

the answer is equal!

why?
even
String s3 = "a" + "b" + "c"
if (s1==s3) .....

will be equal

but
String s4 ;
s4 = "b";
s4 = "a" + s4;
s4 += "c" ;
if (s1 == s4)....

NO it is not equal

but 

s1.equals(s4)

Yes it is equal!

Recursion

GNU ::= GNU is not Unix
"recursive acronym"

----------------

name list ::= name, namelist | name



Fibonacci Numbers
F(0) = 0
F (1) = 1
F(k) = F(k-1) + F(k-2)
int fibonacci (int k) {
if (k==0) return(0);
if(k==1) return(1);
return(fibonacci(k-1) + fibonacci(k-2));
}