A question from my text

Question

In my text there's a self-test question that looks easy but I couldn't figure out., as follows. Note that every detail exactly appers in the text. The question asks what output is produced. The answer is "Positive." Why?
int number = 7;
boolean isPositive = (number>0);
if (number>0);
number = -100;
if (isPositive)
System.out.println("Positive.");
else
System.out.println("Not positive.");

Answer 1

In my text there's a self-test question that looks
easy but I couldn't figure out., as follows. Note
that every detail exactly appers in the text. The
question asks what output is produced. The answer is
"Positive." Why?
int number = 7;
boolean isPositive = (number>0);
if (number>0);
number = -100;
if (isPositive)
System.out.println("Positive.");
else
System.out.println("Not positive.");Why? Here's why,
int number = 7;1.) You declare a variable (A variable is a named placeholder for storing information during program execution) that can hold an int value and you assign literal 7 to it. "number" is our identifier here. (An identifier is a name given to a specific variable).
boolean isPositive = number > 0;2.) You test if identifier number is greater than to 0 (which is logically wrong because a positive number is greater than or equal to 0) and assigned the boolean value to a variable named "isPositive". Now what will be the value of isPositive? is 7 greater than or equal to 0? Of course true. (remember that after evaluating the expression 7 >= 0, the isPositive now holds a true value okay? And you are also wondering why 7 >= 0 is evaluated first before the assignment, thats because assignment operator in Java is right associative, remember?
PUC3A (Prefix, Unary, Creational, Conditional, Cast, Assignment) operator are all right associative meaning they are evaluated from right to left, okay? Review your Java Operator Precendence and Associativity). I remove the () operator because it isnt necessary because >= operator has a higher precendence than = operator. Okie!
if (number>0) ;3.) Now, a single selection stucture (A single selection structure is used to select or ignore an action) "if" tests if identifier number is greater than 0 (as I said logic error, this should be >=) which is evaluated to true because 7 is greater than or equal to 0, but it follows an empty statement ";" see? So nothing is executed. I think you just mistype and what you really want is to change the value of identifier number to -100 if that identifier number is positive, Am I right?
number = -100;4.) You change the value of identifer number to -100, from 7 to -100. Does this statement change the value of our identifier isPositive? Definitely NO!
if (isPositive) // #snif
        System.out.println("Positive.");5.) This statement tests isPositive and what is the value of identifier isPositive again? The value is true right? Then what happen is it prints "Positive".
else
         System.out.println("Not positive.");6.) This statement will only execute if expression (see #snif) evaluates to false.
By the way
if(expression)
        statement;
else
        statement;is double selection structure because it selects between two courses of action. Thats why. Okay? Am I clear? Am I right? ^_^ Thank you.
-Ronillo