ITK 177 spring 2011

ITK 177 spring 2011 PowerPoint PPT Presentation

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ITK 177 spring 2011

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1. ITK 177 spring 2011 Shirley White

2. Java fundamentals 2-2

3. Chapter Topics Today we will discuss the following main topics Scope Programming style Using the Scanner class for input Common errors 2-3

4. Quick review -- Predict the output System.out.print("Hearing in the distance"); System.out.print("Two mandolins like creatures in the"); System.out.print("dark"); System.out.print("Creating the agony of ecstasy."); System.out.println(" - George Barker"); How could you fix the spacing issues? 2-4

5. Scope of a variable The extent of access to a variable’s contents Local variables Declared inside a method Only visible inside the method (unless passed) Class variables Class level data Typically private Accessible only through class methods by instances of the class 2-5

6. Programming Style Use of comments Use of whitespace Use of indentation 2-6

7. Commenting review 2-7

8. The Scanner Class To read input from the keyboard The Scanner class is defined in java.util Requires an import statement import java.util.Scanner; Or import java.util.*; NOT import com.sun.java_cup.internal.runtime.Scanner; 2-8

9. The Scanner Class Scanner objects work with A System object associated with the keyboard To create a keyboard Scanner object use Scanner keyboard = new Scanner (; Scanner class methods are listed in Table 2-17 pp 88-89 of the text or in the Java API See example: 2-9

10. Using a Scanner Remember all declarations must appear at the top of your method… Scanner scan = new Scanner(; We will choose between 4 Scanner methods next() nextInt() nextDouble() nextLine() 2-10

11. Do This Create an application to Get and store an integer Get and store a double Get and store a single token name Get and store a multi token phrase Report all data to the screen with labels 2-11

12. Keep your eclipse workspace organized Use a single workspace on your h-drive Maybe a local workspace if you live off campus Make a single java project for each lab & program Can and often will have multiple classes Make a java project for each chapter For work done while reading the text For work done in class Name your projects reasonably 2-12

13. Common errors Mismatched braces, quotations marks, or parentheses Misspelling keywords, class types, method names, or variables names Attempting to use a keyword as a variable or method name Attempting to include whitespace in variable, method name, or class name 2-13

14. More Common errors Attempting to use a variable without a declaration Attempting to use a variable without an intitial value Backwards variable assignment Unintentional integer division Order of operation logic errors 2-14

15. More Common errors Incompatible type assignment Failing to capture returned method values Especially from String methods Leaving out import statements Using the wrong import statement Using // for multiple line comments Incorrectly terminating multiple line comments Etc… 2-15

16. Practice – code this IntegerInput Request, get, and store 3 integers Print the integers in the opposite of the order entered Print the integer division of the 1st divided by the 2nd Print the double division of the 1st divided by the 3rd Print the remainder of the 1st divided by the 2nd End IntegerInput 2-16

17. More Practice – code this StringInput Request and get the user’s full name (storing in 3 strings: first, middle, and last) Store all names with 1st letter capital and others lower case Print the first name in all caps Print the last name in all lowercase Print the full name in Title Case (with spaces between names) Print the full name in CamelCase (no spaces) Print the 3 initials only (in all lower case – no spaces) End StringInput 2-17

18. Questions?

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