Renaming Things in Java

Printing Quick Response Code in Java Renaming Things

To rename a Java element, select the element and then choose Refactor Rename Now, the resulting parameter page differs depending on the kind of element that you select, but in more than a few cases the parameter page is going to have the check boxes shown in Figure 11-1

To see what these check boxes do, look at Listing 11-1

11: Refactor This!

/* * MyFramejava * * Thanks to rose friedman for her help in creating this code */ import javaawtColor; import javaawtImage; import javaawtToolkit; import javaxswingJFrame; public class MyFrame extends JFrame { MyImagePanel panel = null; final Color rose = new Color(255, 0, 100); public MyFrame() { Image rose = ToolkitgetDefaultToolkit()getImage( rosejpg ); panel = new MyImagePanel(rose); } public void changeBackground() { setBackground(rose); } }

Suppose you select the word rose in the final Color rose = new Color(255, 0, 100) declaration Then you choose Refactor Rename, wait for the parameter page in Figure 11-1 to appear and then enter violet in the page s New Name field Here s what happens when you check or uncheck the boxes in Figure 11-1: If you leave the Update References box checked and then accept everything in the preview, Eclipse changes the following two lines:

final Color violet = new Color(255, 0, 100); setBackground(violet);

Eclipse doesn t change any occurrences of the word rose inside the MyFrame constructor (Eclipse understands that you can have different variables, both named rose) If you uncheck the Update References box and then accept everything in the preview, Eclipse doesn t change the name in the call to setBackground:

final Color violet = new Color(255, 0, 100); setBackground(rose);

When you don t check the Update References box, Eclipse modifies only the occurrence that you select If you check the Update Textual Matches in Comments and Strings box and accept everything in the preview, Eclipse makes the following changes:

Thanks to violet friedman for her help in creating final Color violet = new Color(255, 0, 100); ToolkitgetDefaultToolkit()getImage( violetjpg );

Even with this Update Textual Matches in Comments and Strings box checked, Eclipse doesn t change variables inside the MyFrame method Eclipse doesn t change Image rose to Image violet, and doesn t change new MyImagePanel(rose) to new MyImagePanel(violet) While hunting for text in comments and strings, Eclipse ignores everything except whole words In this example, Eclipse doesn t consider changing Systemoutprint( rosey ) to Systemoutprint ( violety ) If you leave the Update Textual Matches in Comments and Strings box unchecked and accept everything in the preview, Eclipse leaves rose friedman and her buddy rosejpg alone In this case, Eclipse doesn t change rose words inside comments or strings Eclipse s Rename refactoring is very smart For example, when you rename an interface s abstract method, Eclipse hunts down all implementations of that method and applies renaming to those implementations

When I was new to object-oriented programming, I obsessed over questions about where things should go For instance, when you pay an employee, you write a check You use a PayrollCheck object Should a PayrollCheck object contain its own write() method, or should a DoPayroll object contain a write(PayrollCheck check) method These days I don t worry about those issues so much, but I still change my mind as I develop a project s code I discover things that didn t occur to me during the design phase, so I move Java elements from one part of my application to another Fortunately, Eclipse helps

11: Refactor This!

Consider the code in Listings 11-2 and 11-3 The PayrollCheck class defines what it means to be a check (something that an employee can take to the bank) And the DoPayroll class writes checks

Listing 11-2: