Class  5  Mon 1/28  Comp 110


Variables - quick review
Program 3
Branches
   Simple
Compound statements


Quick review of variables
--- Java is a strongly typed language
     --- each variable is assigned a data type:  int n1;
     --- you can only assign legal values of the specified type
             to the variable.  Ex.  n1 = "Comp110"  is not legal.
--- Our most common data types
   int
   String
   boolean
   double

--- a data type is
   i) a set of values
  ii) a set of operations on those values


Simple branch
   if( x > 5 ) System.out.println("A");

A branch is a fork in the road, or, more formally, 
a change in the flow of control.

Default flow of control is: top to bottom, left to right.
Just like reading a book.

In each branch we ask a question.  Each question must be simple
enough to have a true or false answer.  The answer determines
which group of Java statements (i.e. which branch) is executed
by the computer. 





Integers comparisons = question we can ask in Java
3 == x   
x != z  
x > y

String comparison requies 'equals'. Ex:

if(str.equals("comp110")) SOP("rocks");

A compound statement bundles together multiple statements

if(str.equals("comp110")) {
   SOP("rocks");
   SOP(" totally");
}


Nested branch
if(raining) Top up
else if(really cold) Top up
else Top down


Compound condition
if(raining || really cold) Top up
else Top down