1. If Statements If statements: allow the computer to make a decision Syntax: if (some condition) { then do this; } else { then do that; } no semicolons on the If or Else lines!

2. Comparing variables When comparing variables (except Strings), use the double-equals ( = = ), NOT the equals sign! example: if (GPA = = 3.2)… “Does not equals:” ! = Greater than > Greater than or equal to >= Less than < Less than or equal to <=

3. If-else if If there are more than 2 possibilities, you must use the “else if” Your final possibility should be the only “else” Syntax: if (condition_1) { Statement_1; } else if (condition_2) { Statement_2; } else { Statement_3; }

4. And vs. Or “and”  && (Statements will execute only if both conditions are true) “or”  | | (Statements will execute if one condition is true) if ( score >= 80 && score < 90 ) { grade = ‘B’; }

5. A common mistake: if (score >= 80 && < 90) You must put a variable before each,==, =, etc….. So the correct code would be: if (score >= 80 && score < 90)

6. When an and statement is false… Very important: when && is used, once the compiler finds a part of the condition that is false, it ignores the rest of the condition, as well as whatever is inside the attached if-statement. Example: int x = 0; int y = 0; if (x = = 1 && y = = 0) { System.out.println(“Hi”); } In this example, once the compiler sees that x does not equal 1, it ignores everything that follows the &&, including y = = 0. If this had been an || instead of a &&, then the condition would be true, and the if-statement would execute (“Hi” would be displayed).

7. When comparing Strings in an if statement, you DO NOT use = = Instead, you must use.equals(“ “) or.equalsIgnoreCase(“ “) String dog = “Fido”; if (dog == “Fido”) // false if (dog.equals(“Fido”)) // true if (dog.equalsIgnoreCase(“fido”)) // true if (dog.equals(“fido”)) // false ***to use “does not equal” with a String: if (!(dog.equalsIgnoreCase(“fido”)))

8. Demo: DemoIf

9. Java uses order of operations (PEMDAS), and modulus division is at the same level as multiplication and division. So, Java really uses PEMMDAS. Example: int x = 5 + 8 / 5 * 3 – 10 % 6; what would this equal? = 5 + 1 * 3 – 4 = 5 + 3 – 4 = 4

10. Assignments 1.(SayMyName)  Prompt the user to enter his or her first name, then (separately) their last name.  If the first OR last name is Walter, give copious praise to the user.  If the first name is Walter and the last name is White, display “Heisenberg.”  **Test your program: only one of the above results should display, never both.** 2.(Numbaz)  Prompt the user to enter a test score between 0 and 100.  Display what letter grade the score corresponds to. (90-100 = A, 80-89 = B, etc)  Display whether the score is even or odd.  If it is even, display whether or not it is prime.  Display whether or not the score is divisible by 7.  If so, display whether or not it is a multiple of 14.  If the score is 97, display “Yay”  If the score is not between 0 and 100, shame the user.