Figure 10-5: Selecting in Java

Creator QR Code 2d barcode in Java Figure 10-5: Selecting

The code in the Refactored Source pane doesn t necessarily keep up with things you do to the preview page s check boxes For instance, in Figure 10-6, the Refactored Source pane can contain declarations even after you uncheck the MyOtherClass branches Regardless of what you may see in the Refactored Source pane, the boxes you check in the top half of the preview page have the final authority These boxes determine what Eclipse does (or doesn t do) with your code You can t edit the code in either the Original Source or the Refactored Source panes of Figure 10-6 You can copy the code (for the purpose of pasting it some other place) but you can t delete or otherwise modify the code in these panes To change the way refactoring works, you must use the check boxes in the top half of the preview page 6 Click OK The preview page disappears 7 Notice how your code has changed Because of the things you do on the preview page, Eclipse restores the original Java source code of Listing 10-1 the code in which only MyClass contains i and display declarations This section s instructions do the opposite of what the Parameter pages section s instructions do The Parameter page instructions go from Listing 10-1 to Listing 10-2, and this section s instructions go from Listing 10-2 back to Listing 10-1 Hey, wait! That sounds like Undo!

In fact, applying Refactor Undo can roll back a refactoring operation s effects But remember this: If you change anything after you refactor, then you can no longer apply the Refactor Undo or Refactor Redo actions When I say change anything I mean change the code with anything other than another refactoring action For example, imagine that you follow the instructions in this chapter s Parameter pages section These instructions take you from Listing 10-1 to Listing 10-2 After following the instructions, you click your mouse inside the editor and add a blank space somewhere in the code That blank space puts the kibosh on any future Undo operation After adding the blank space, you can no longer use Refactor Undo to go back to the code in Listing 10-1 No, undoing your addition of the blank space doesn t help The Refactor Undo action simply refuses to perform

A refactoring operation can involve three kinds of pages: parameter pages, a preview page, and a problem page This section describes a problem page Remember, you don t have to retype the code in Listings 10-3 and 10-4 You can download the code from this book s Web site 1 Create a project containing the code in Listings 10-3 and 10-4 2 Select the computeTax method in Listing 10-3, and then choose Refactor Move Eclipse opens the Move Static Members parameter page (See Figure 10-7)

3 Type CashRegister in the Destination Type field When you type CashRegister you tell Eclipse that you want to move the

computeTax method to the code in Listing 10-4

4 Click OK Oh, oh! Eclipse shows you the problem page of Figure 10-8 According to this problem page, moving computeTax to the CashRegister class

may not be a good idea After all, the computeTax method refers to a taxRate field The code inside the CashRegister class can t access that private taxRate field And Eclipse isn t willing to drag the taxRate declaration to the CashRegister class for you

5 Live dangerously In spite of everything that you see in the problem page, click Continue When you click Continue, Eclipse bows reluctantly to your wishes But the new refactored code has errors, as you can see in Figure 10-9 Of course, for a short time, you may be able to tolerate a few errors If you cut and paste instead of refactoring, you probably have some errors to clean up anyway Good refactoring means going from correct code to correct code (without having any incorrect code in between) But sometimes you can t afford to do good refactoring That s when the Continue button on the problem page comes in handy