Class 2  Mon 1/14   Comp 110

Java security
--- A Java update will be issued tomorrow.  It patches
a security flaw that arises when running Java in your browser
(not Eclipse).  MAKE SURE YOU INSTALL IT
---  A good practice (that I am adopting for the future) is
to use Firefox with the 'noscript' add-on.  This will allow you
to control which web sites that are allowed to run executable
code (including Java) in your browser.  


5 Building Blocks of Every Program
  Variable - data
  Branch - asking a question and making a choice
  Loop - repetitive
  Method - bundle of Java statement + variables they share
  Class - bundle of methods + variables they share

Listing 1.1 and 1.2 illustrate variable, method and class
(no branch or loop)





Peanut Butter and Jelly
......
Grasp lid of PB jar
Twist counterclockwise 3 full rotations
Remove lid
Place lid on table
Pickup knife
Insert knife into PB jar
Remove knife
Swipe knife on bread
......


INCLASS EXERCISE - turn in one solution per group,
print your names 

Program robot to make one sandwhich for everyone



Lesson - must PRECISELY define problem before starting
to program


Given instructions to make 1 PB&J, program robot
to make one sandwhich for each of the 136 students
in the class

count = 0
make 1 PB&J
if( count == 136 ) we are done
else go back to 'make 1 PB&J'


Writing these instructions in more Java-like form

count = 0
while( count < 136 ) 
   make 1 PB&J
   count = count + 1