1. Chapter 2© copyright Janson Industries 20141 Java ▮ Java/PC programming environment ▮ Java syntax rules ▮ Java documentation ▮ Java/RAD coding example This presentation is stored in 4thed.Ch02.ppt Non-graded assg

2. Chapter 2© copyright Janson Industries 20142 Setting up the environment ▮ Files are identified by a name, myfile.doc, and location (aka path), C:\Program Files\ ▮ When a file is identified by the path and file name, C:\Program Files\myfile.doc, it is considered a fully-qualified reference ▮ If a file is referred to with only name, myfile.doc, it is a non-qualified reference

3. Chapter 2© copyright Janson Industries 20143 Setting up the environment ▮ Having to type the fully-qualified name of every file is time consuming and error prone ▮ The PATH system variable tells Windows where to search for non-qualified file references ▮ The CLASSPATH indictates where to search for non-qualified.class file references

4. Chapter 2© copyright Janson Industries 20144 Setting up the environment ▮ Defining Path and CLASSPATH every time is time consuming ▮ Could create a.bat program called init ▮ Init.bat would contain the commands to define Path and CLASSPATH ▮ Simply run init each time ▮ Or, define the system variables permanently

5. Chapter 2© copyright Janson Industries 20145 Setting the Path Right click: “Computer” Choose: Properties Click: Advanced system settings Click: Environment Variables button

6. Chapter 2© copyright Janson Industries 20146 In the System Variables pane: Click the variable Path Then the Edit button Setting the Path

7. Chapter 2© copyright Janson Industries 20147 In the Edit System Variable window, add to the end of the Path value: ;c:\jdk\bin Then Click the OK button Change CLASSPATH by adding the path of your java application (i.e..class files) to the variable ; c:\ Setting the Path (Windows 7)

8. Chapter 2© copyright Janson Industries 20148 Setting the Classpath ▮ If there is no classpath environment variable, create one ▮ Click New and specify the variable name (classpath) and value

9. Chapter 2© copyright Janson Industries 20149 General steps to run on PC ▮ Save the source code (E.g. Customer.java) ▮ Bring up the command prompt ▮ Set path (path=f:\jdk\bin) to identify the loaction of the javac and java commands ▮ Set classpath (Set classpath=.;f:\) to identify location of java class files (i.e..class files) ▮ Or, change the environment values ▮ Convert to byte code (javac Customer.java) ▮ Run the program (java Customer)

10. Chapter 2© copyright Janson Industries 201410 Java Concepts ▮ Java “program” is called a class ▮ Java classes grouped into projects and packages ▮ Java classes comprised of global/class variable definitions and methods ▮ Methods contain executable statements and local/method variable definitions ▮ Are you familiar with what variables do?

11. Chapter 2© copyright Janson Industries 201411 Java Language Organization Project Package Package Package Class Class Class Variable Method Method Method Variable Variable Statement Statement

12. Chapter 2© copyright Janson Industries 201412 Java Language Concepts ▮ Let’s concentrate on the source code ▮ Java classes comprised of class ( global) variable definitions and methods ▮ Methods contain executable statements and method ( local) variable definitions

13. Chapter 2© copyright Janson Industries 201413 Classes Class Variable Variable Method Method Method Variable Statement Statement zClass comprised of class variable definitions and methods zMethods contain method variable definitions and executable statements

14. Chapter 2© copyright Janson Industries 201414 Java Class Example // Customer.java public class Customer { String custName, custStreet, custCSZ; public Customer() { custName = "No Name"; custStreet = "No Street"; custCSZ = "No CityStateZip"; } public void printCustInfo(){ System.out.println("CUSTOMER NAME IS: " + custName); System.out.println("CUSTOMER STREET IS: " + custStreet); System.out.println("CUSTOMER CSZ IS: " + custCSZ); } public static void main( String[] args ) { Customer aCust = new Customer(); aCust.custName = "Joe Customer"; aCust.printCustInfo(); } methods Class variables statements Method variable

15. Chapter 2© copyright Janson Industries 201415 Classes ▮ Divided into the header and the body ▮ Header defines: ▮ The source code as a class (e.g. “class”) ▮ Access allowed (e.g. “private”, “public”) ▮ The name of class ▮ Must begin with an upper case letter ▮ Must match.java file name ▮ Body is enclosed in braces and contains class variables and methods ▮ Simple class header example: ▮ public class Customer { BODY }

16. Class names  Are case sensitive!  Begin with a capital letter  No spaces Body of class begins and ends with braces Chapter 2© copyright Janson Industries 201416 Class Definition: Header Bodypublic class Customer { class variables method{} } Java Class Class access Class name “A class contains a template for creating objects”

17. Chapter 2© copyright Janson Industries 201417 Java Method ▮ Comprised of a header/definition and body ▮ Header/definition comprised of: ▮ Modifiers (e.g. private, public, static) ▮ Return value type (e.g. void, String) ▮ Method name begins with a lower case letter (e.g. “getMailingLabel”, “main”) ▮ Parameter(s)/received value(s) in parenthesis (e.g. (String name), (int age), () means no params)

18. 18 Java Method ▮ When a parameter is define must specify the data type and the variable name to hold the data ▮ So with (String name) String is the data type and the variable that will hold the passed value is name ▮ (int age), data type is integer (int) and the variable name is age

19. Chapter 2© copyright Janson Industries 201419 Java Method ▮ Method header/definition examples: ▮ public void setCustomerName(String custName) ▮ public String getMailingLabel() ▮ public static void main(String[ ] args) ▮ public void setTaxRate(double taxRate)

20. Chapter 2© copyright Janson Industries 201420 Java Method ▮ Method "access" modifiers (cont’d): ▮ Private methods: ▮ only accessed by other methods within the class ▮ Public methods: ▮ can be accessed by objects external to the class ▮ comprise the class “interface” ▮ Variables can also be public or private ▮ public can be accessed by objects external to the class

21. Chapter 2© copyright Janson Industries 201421 Java Concepts ▮ Java classes can be invoked many ways ▮ 2 primary ways ▮ Run with the java command ▮ Instantiated ▮ An object (aka an instance) of the class type is created ▮ An object is an "instance of a class" and is usually associated with a variable

22. Chapter 2© copyright Janson Industries 201422 Java Concepts ▮ If java class is invoked with the java command: ▮ main method bytecode converted to machine language ▮ main method machine language loaded into main memory ▮ main method is executed ▮ If Java class is instantiated: ▮ Entire class' bytecode converted to machine language and loaded into main memory ▮ i.e. An object of that class type is created ▮ Class (global) variables created ▮ constructor method is executed

23. Chapter 2© copyright Janson Industries 201423 Specialized Methods ▮ Constructors are methods that: ▮ Can not return any values ▮ Have the same name as the class ▮ Are run when the object is instantiated ▮ Are used to initialize variables and perform setup operations (e.g. open files, assign user supplied values, establish communication links, etc.) ▮ Static method “main”: ▮ Java command invokes main method in applications (main is not run when object instantiated) ▮ Main method header must be defined precisely as follows:

24. Chapter 2© copyright Janson Industries 201424 public static void main(String[ ] args) main Method No values returned Any class can use The method expects an array of String variables (called args) When main is invoked, object not created Method name

25. Chapter 2© copyright Janson Industries 201425 Notice how much the class and constructor method headers look alike What's the difference? Customer has a class header, constructor, and main method that follow the previously defined rules

26. Chapter 2© copyright Janson Industries 201426 Method body ▮ Comprised of: ▮ variable definitions ▮ executable statements ▮ Enclosed in braces { } public Customer(String name, String street, String cityStateZip) { private String custName = null; private String custStreet = null; private String custCityStateZip = null; custName = name; custStreet = street; custCityStateZip = cityStateZip; }

27. Chapter 2© copyright Janson Industries 201427 Java Language ▮ Variables usually defined at the beginning of a class or method ▮ Variable definitions: Access modifier (e.g. “private”, “public”) (optional) Data type (e.g. “int”, “String”) Name (e.g. “custID”, “custName”) Initial value (optional) End with a semicolon (;) ▮ Examples: private int custID = 0; public String custName = null;

28. Chapter 2© copyright Janson Industries 201428 Java Language Multiple line comment Single line comment Multiple line comment ▮ Comment examples: /* This is an example */ /** This is an example */ public int custID = 0; // This is an example ▮ In RAD, comment out and uncomment any line(s) by selecting and pressing CTRL + /

29. Chapter 2© copyright Janson Industries 201429 Programming Conventions ▮ Class header and start of body defined public class Customer { ▮ Class variables defined private String custCityStateZip = null; private static int lastCustID = 100000; ▮ Methods defined public Customer(String cityStateZip) { custCityStateZip = cityStateZip; int custID = lastCustID + 1; } ▮ Class body ended }

30. Chapter 2© copyright Janson Industries 201430 Source Code Rules ▮ Statements end with a semicolon (;) private String custCityStateZip = null; private static int lastCustID = 100000; ▮ Very forgiving re: extra spaces and lines private String custCityStateZip = null ; public Customer(String cityStateZip) { custCityStateZip = cityStateZip; int custID = lastCustID + 1;} ▮ To invoke a class method from another class method (and pass many parms): this.methodName(parm, parm, etc); returnValue = this.methodName(parm, parm, etc.);

31. Chapter 2© copyright Janson Industries 201431 Source Code Rules ▮ To invoke a method from outside the class, instantiate an object of the class type, create a variable of the class type and assign the object to the variable : ▮ Syntax: ClassName variableName = new ClassName(); Example: Customer myCust = new Customer(); ▮ Then invoke the object’s method: Syntax: variableName.methodName(); Example: myCust.printCustInfo();

32. Chapter 2© copyright Janson Industries 201432 Source Code Rules ▮ Weird? Not really. To use Word Processing commands, don’t you need to create a document? ▮ To use queue commands, doesn’t a queue have to be created (and referenced in each command) ? ▮ So why shouldn’t you have to create a Customer object to use a customer function? Customer myCust = new Customer(); myCust.printCustInfo();

33. Chapter 2© copyright Janson Industries 201433 Class header Class variables Method header Statements Method header Statements Method header Statements What will be the result of running Customerc2sl31 as an application?

34. Chapter 2© copyright Janson Industries 201434 Execution Results ▮ main method bytecode converted to machine language and loaded into main memory ▮ First statement in main executed: a Customer object is created. This means: ▮ The entire Customer class’ bytecode is converted to machine language and loaded into main memory ▮ 3 String objects are created, 3 String class level variables (custName, custStreet and custCSZ) are created, and the String objects are assigned to the variables ▮ The Customer object’s constructor is executed. This means:

35. Chapter 2© copyright Janson Industries 201435 Execution Results ▮ 3 String objects are created with the text “No Name”, “No Street”, “No CityStateZip” ▮ 3 new String objects are assigned to the variables custName, custStreet and custCSZ ▮ Execution returns to the first statement in the main method and ▮ The Customer variable aCust is created ▮ The Customer object is assigned to aCust ▮ Second statement in main executed: ▮ A String object is created with the text “Joe Customer” ▮ The new String object with the value “Joe Customer” is assigned to the Customer object’s class level String variable custName

36. Chapter 2© copyright Janson Industries 201436 Execution Results ▮ Third statement in main executed: the Customer object’s printCustInfo method invoked. This means: ▮ First println statement is executed, what is shown? ▮ Second println statement is executed, what is shown? ▮ Third println statement is executed, what is shown?

37. Chapter 2© copyright Janson Industries 201437 What will be the result of running this? Let’s create a new class and run… Proving main vs. constructor

38. Chapter 2© copyright Janson Industries 201438 Click on the src folder name and then File, New, Class

39. Chapter 2© copyright Janson Industries 201439 Specify the name of the new class (Cust1), click Finish

40. Chapter 2© copyright Janson Industries 201440 Starts you with a framework Move the cursor and start typing

41. Chapter 2© copyright Janson Industries 201441 Enter the source code and run What are the results and why?

42. Chapter 2© copyright Janson Industries 201442 Exporting: Moving an app from RAD to the production environment Click FILE then EXPORT

43. Chapter 2© copyright Janson Industries 201443 Click File system then Next

44. Chapter 2© copyright Janson Industries 201444 In real world, usually export to JAR (Java ARchive) files. They are compressed files.

45. Chapter 2© copyright Janson Industries 201445 1. Select the java files to export...click browse and specify the location 2. Enter export destination or... 3. Click OK 4. Click Finish

46. Chapter 2© copyright Janson Industries 201446 Click Finish Notice options to create directories and overwriting files

47. Chapter 2© copyright Janson Industries 201447 Go out and verify Cust1.java is there.

48. Chapter 2© copyright Janson Industries 201448 Open with notepad to display

49. Chapter 2© copyright Janson Industries 201449 javac and java Make sure classpath and path variables are set

50. Chapter 2© copyright Janson Industries 201450 Exporting ▮ Moving between/setting up environments is one the most difficult thing (conceptually) for new programmers ▮ Programmers develop apps within an IDE (like RAD) and export to the production environment

51. Chapter 2© copyright Janson Industries 201451 Exporting ▮ This is where packages can mess you up! ▮ Ex. For a Customer class stored in project Proj1 and package C1: ▮ Customer must have a package statement at beginning of class package C1; ▮ Class name is now considered C1.Customer

52. Chapter 2© copyright Janson Industries 201452 Exporting and Running ▮ When file exported to Windows, Customer file must be in a directory/folder called C1 ▮ Project and packages (except default pkg) implemented in Windows as directories ▮ So, if "create directory structure" specified ▮ Both Proj1 and C1 directories are created ▮ Also a src folder is created ▮ javac Customer will fail because Customer not class name ▮ javac C1/Customer will fail because Proj1 not in classpath

53. Chapter 2© copyright Janson Industries 201453 Exporting and Running ▮ Need to add Proj1 to the classpath and refer to the class with package name included in the class name ▮ Set classpath = f:\Proj1\src ▮ javac C1/Customer ▮ Be careful of directory structure when exporting! ▮ I suggest just exporting the package as a directory

54. Chapter 2© copyright Janson Industries 201454 ▮ In other words, on the export window choose the third option "create only selected directories" ▮ Then click the java file and the package's checkboxes ▮ I.e. select the package/directory ▮ This will result in a folder with the package name and the java file inside it Exporting and Running

55. Chapter 2© copyright Janson Industries 201455 ▮ No project folder or src folder will be created ▮ You wont have to add them to the path ▮ Still need to set the path to the location of the package/folder though ▮ Then issue javac command with the package/folder name and the java file name Exporting and Running

56. Chapter 2© copyright Janson Industries 201456 Graded Assgs (class room based class) ▮ Export out of RAD workspace onto thumb drive ▮ Source and.class files ▮ Create batch file so it executes the new thumb drive files ▮ Assgs will be graded in class ▮ Display source files (including bat file) in notepad ▮ Run the app ▮ I will run test data

57. Chapter 2© copyright Janson Industries 201457 Non - Graded Assgs ▮ Export file(s) or package (recommended) out of RAD workspace as a jar file ▮ Source and.class files ▮ Send the jar file as an email attachment to wsjavaws@yahoo.com wsjavaws@yahoo.com ▮ I will acknowledge receiving them within one business day ▮ If you do not hear from me, I did not receive them

58. Chapter 2© copyright Janson Industries 201458 Non - Graded Assgs ▮ How to check you exported a jar file correctly ▮ Create a new project ▮ Import the jar into the project by ▮ Choosing Import archive file ▮ Specify the jar file ▮ Expand the project and confirm that all the packages and source code files are there

59. Chapter 2© copyright Janson Industries 201459 Graded Assgs ▮ Export package(s) or entire project(s) out of RAD workspace as a jar file ▮ Source and.class files ▮ Send the file(s) as an email attachment to wsjavaws@yahoo.com wsjavaws@yahoo.com ▮ I will acknowledge receiving them within one business day ▮ If you do not hear from me, I did not receive them

60. Chapter 2© copyright Janson Industries 201460 Graded Assgs ▮ How to check you exported the jar correctly ▮ Create a new project ▮ Import the jar into the project by ▮ Choosing Import archive file ▮ Specify the jar file ▮ Expand the project and confirm that all the packages and source code files are there

61. Chapter 2© copyright Janson Industries 201461 Documentation ▮ Online documentation available. Ex: ▮ Gives an overview of the JDK supplied classes and a short description of the methods ▮ The JDK classes grouped into packages! http://download.oracle.com/javase/8/docs/api/

62. Chapter 2© copyright Janson Industries 201462 Shows a brief description of all packages in V8 Or click a class in the index on the left Click the package name to see all classes in the package

63. Chapter 2© copyright Janson Industries 201463 Shows a hierarchy for the class Brief description and examples

64. Chapter 2© copyright Janson Industries 201464 A list and brief summary of the methods in the class

65. Chapter 2© copyright Janson Industries 201465 Documentation ▮ You can generate the same documentation for your classes ▮ First, you may have to tell RAD where the javadoc command is (in the JDK) ▮ In our case: F:\jdk\bin\javadoc.exe

66. Chapter 2© copyright Janson Industries 201466 Right click the class and select Export

67. Chapter 2© copyright Janson Industries 201467 Select Javadoc and click Next

68. Chapter 2© copyright Janson Industries 201468 Specify where the documentation should go, click Finish RAD should know that javadoc is in the JDK in RAD

69. Chapter 2© copyright Janson Industries 201469

70. Chapter 2© copyright Janson Industries 201470 Console shows Javadoc messages

71. Chapter 2© copyright Janson Industries 201471.html file with same name as class is there Double click to display in browser

72. Chapter 2© copyright Janson Industries 201472 The “signature” of each method is shown Signature = method name + parameters The signature uniquely defines each method, not the name

73. Chapter 2© copyright Janson Industries 201473 Non-graded Assg ▮ Create Cust1 ▮ Export Cust1 and Run ▮ Export Cust1 documentation ▮ Send Cust1.java, Cust1.class, and Cust1.html files as email attachments to wsjavaws@yahoo.comwsjavaws@yahoo.com