Figure 8-2: Everybody gets paid in Java

Generate Code 3 of 9 in Java Figure 8-2: Everybody gets paid

Back in Listing 8-1, notice the comma inside the %,2f placeholder The comma tells the program to use grouping separators That s why, in Figure 8-2, you see $5,00000, $7,00000, and $10,00000 instead of $500000, $700000, and $1000000 Grouping separators vary from one country to another For instance, in France, to write the number one thousand (mille), you write 1 000,00 Java can Frenchify your number automatically with a statement like out print(new javautilFormatter()format(javautilLocale FRANCE, %,2f , 100000)) For details, see the API (Application Programming Interface) documentation for Java s Formatter and Locale classes

Working with Disk Files (A Brief Detour)

In previous chapters, programs read characters from the computer s keyboard But the code in Listing 8-2 reads characters from a specific file The file (named EmployeeInfotxt) lives on your computer s hard drive

This EmployeeInfotxt file is like a word processing document The file can contain letters, digits, and other characters But unlike a word processing document, the EmployeeInfotxt file contains no formatting no italics, no bold, no font sizes, nothing of that kind The EmployeeInfotxt file contains only ordinary characters the kinds of keystrokes that you type while you play a guessing game from s 5 or 6 Of course, getting guesses from a user s keyboard and reading employee data from a disk file aren t exactly the same In a guessing game, the program displays prompts, such as Enter an int from 1 to 10 The game program conducts a back-and-forth dialogue with the person sitting at the keyboard In contrast, Listing 8-2 has no dialogue This DoPayroll program reads characters from a hard drive and doesn t prompt or interact with anyone Most of this chapter is about code reuse But Listing 8-2 stumbles upon an important idea an idea that s not directly related to code reuse Unlike the examples in previous chapters, Listing 8-2 reads data from a stored disk file So in this section, I take a short side trip to explore disk files

The code in Listing 8-2 doesn t run unless you have some employee data sitting in a file Listing 8-2 says that this file is EmployeeInfotxt So before running the code of Listing 8-2, I created a small EmployeeInfotxt file The file is shown in Figure 8-3; refer to Figure 8-2 for the resulting output

When you install JCreator from this book s CD-ROM, the computer copies my EmployeeInfotxt file exactly where you need it in the project directory for Listings 8-1 and 8-2 So you can run this section s code without worrying about the EmployeeInfotxt file

Even though you re not worried about it, you may want to see the EmployeeInfotxt file in JCreator s editor Who knows You may want to change some of the data in the file Here s how you can bring the file into the Editor pane: 1 With JCreator open, choose File Open Workspace An Open dialog box appears 2 In the Open dialog box, select 08jcw, and click Open The 08 workspace fills JCreator s File View pane 3 In the File View pane, right-click the Listings0801-02 project A context menu appears 4 In the context menu, select Show All Files Some additional filenames appear under the Listings0801-02 branch of the File View s tree One of these other filenames is EmployeeInfotxt 5 In the File View s tree, double-click EmployeeInfotxt When you write your own code, you may need to create files like my EmployeeInfotxt file Here s how you do it: 1 In the File View pane, right-click the name of a project Then choose Add New File from the context menu that appears JCreator s File Wizard opens to the File Path tab Look for the File Wizard s tab names (File Type and File Path) on the left side of the File Wizard window Check to make sure that the name File Path is highlighted If not, then click the name File Path before moving on to the next step 2 In the Name field, type the name of your new data file You can type any name that your computer considers to be a valid file name For this section s example, I used EmployeeInfotxt, but other names, such as EmployeeInfodat, EmployeeInfo, or Employees12301dataFile, are fine I try to avoid troublesome names (including short, uninformative names and names containing blank spaces), but the name you choose is entirely up to you (and your computer s operating system, and your boss s whims, and your customer s specifications) Always include a dot in File Path tab s Name field If the filename has no extension, add a dot at the end of the name For instance, to create a file named EmployeeInfo (not EmployeeInfotxt or EmployeeInfo dat), type EmployeeInfo exactly as you see it here If you don t type your own dot anywhere in the Name field, JCreator adds a default extension to the filename (turning EmployeeInfo into EmployeeInfojava)