1. Announcements Quiz 1 Next Monday

2. int : Integer Range of Typically –2,147,483,648 to 2,147,483,647 (machine and compiler dependent) float : Real Number (i.e., integer part, decimal part, and exponent part) Range of Typically (+/-) 10e-45 to 10e38 double : Larger Real Number ((+/-) 10e-324 to 10e308) char : Character Built-In (or Primitive) Data Types for Variables

3. Can Use Letters: Remember That JAVA is Case Sensitive (e.g., NumWidgets Is Not the Same as numwidgets ) Can Use Digits 0-9, $, and Underscore Cannot Start with a Digit Cannot Contain Spaces or Other Characters Cannot Use JAVA Keywords Naming Variables in JAVA: Identifiers

4. Should Use a Meaningful, Descriptive Name so that Variable’s Use Is Easily Understood: Examples: counter, second, minute, length, width Be Consistent with Case; Usually Lower Case with Upper Case for Second Part of Variable Name Examples: averageRainfall, totalStudentGrades, maxBuildingHeight, minPackageWeight; Naming Variables (Cont)

5. Constant: An Identifier that Is Initialized to a Value that Cannot Change Usually Declared at Top of Program using Keyword final Standard Naming of Constants Is to Use All Upper Case Letter with or without Underscore between Words All Constants Should Be Initialized Syntax: final int MAXHT = 100; Named Constants

6. Easier to Understand Easier to Modify Example: Compare using Number 100 in Program versus Constant MAXHT Advantages of Constants

7. public class MyProgram { public static void main( String [ ] args) { final int MAXHT = 100;... currentHeight > MAXHT... bridgeHeight == MAXHT... bridgeHeight + newAddition >= MAXHT... // used MAXHT 223 times in this program } Named Constants

8. Constants Whose values Are Already Known: Characters (Specified Inside Single Quotes): ‘A’, ‘a’, ’5’, ’ ‘, ’\n’ (newline), ’\0’ (NULL Character) Integers: 10, 1345, -34 Float or Double: 2.3, -45.18, 10.6e6 String (Specified Inside Double Quotes): “HELLO”, “What a great deal.”, “5” Literal Constants (Values)

9. Also Known as I/O Output : System.out.println(“Hello World!!”); Input (Scanner): import java.util.Scanner; Scanner scan = new Scanner(System.in); scan.nextInt(); scan.nextFloat(); scan.nextDouble(); scan.next(); //String to whitespace scan.nextLine(); // String to end of line All Wait until User Inputs Particular Type Input and Output

10. import java.util.Scanner; public class MyProgram { public static void main( String [ ] args) { Scanner scan = new Scanner(System.in); int numEntered; System.out.print(“Enter an integer:”); /// The following waits until user hits Enter numEntered = scan.nextInt(); System.out.println(“You entered: “ + numEntered); } Input and Output Example

11. Strings in java.lang package Java.lang imported automatically Characters and Strings

12. Declaration: String yourName; Assigning a Value to a String: yourName = “A. Goose”; String Constants (Values) Must Be Enclosed in Double Quotes JAVA Strings

13. import java.util.Scanner; public class MyProgram { public static void main( String [ ] args) { Scanner scan = new Scanner(System.in); String lastname; System.out.print(“Enter last name:”); lastname = scan.next(); System.out.println(“You entered: “ + lastname); } Input String Example

14. Expressions Expression: A Sequence of One or More Identifiers and Operators that Evaluates to a Value Operator: A Symbol Expressing a Way to Modify a Value or Values (e.g., + for Addition) Operand: A Value Being Modified by an Operator Example Expressions: 5 currentHeight currentHeight + 10

15. Arithmetic Expressions Standard Arithmetic Operations Can Be Performed: Addition, Subtraction, Multiplication, Division Standard Arithmetic Operators Can Be Used for These Operations: +, -, *, / Others: % - “Modulo (Mod)” – Remainder after Integer Division -- Decrement (Subtract 1) ++ Increment (Add 1)

16. Order of Operations Precedence: Level of Importance of Operations Multiplicative Operators Have Higher Precedence than Additive Operators: *, /, % Higher +, - Lower Associativity: Order of Operation for Equal Level Precedence Most Operators Have Left-to-Right Associativity Use Parentheses to Force Differing Precedence of Operations

17. Know for the Quiz All Terms (Underlined Items) Variable Declaration, Initialization, and Assignment Constant Declaration Expressions Operators Input (Scanner) and Output (System.out) Everything in Homework through Lab 2