6.9. Scrapbook Pages

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6.9. Scrapbook Pages A scrapbook page is a way to create and test snippets of code without all the trappings of normal Java code. In some ways, it's like working in a scripting language, but you have the full expressiveness of Java in addition to being able to make calls into any of your code or any of the system libraries. To create a scrapbook page, select File New Other… Java Java Run/Debug Scrapbook Page. Enter the name of the page�for example, test�and click Finish (or just press Enter). A new editor page will open for test.jpage. In the blank scrapbook page, try typing in an expression like 123/456, press Ctrl+A to select the expression, and press Ctrl+Shift+D (Run Display) to run it and display the result. (The answer in this case is (int) 0 because both numbers are integers and the result was truncated.) Note that the result is selected, so you can copy it quickly (or press Backspace to remove it from the page). Next, try entering Math.PI and displaying its result. This works because the scrapbook page already has all the system libraries imported, including the Math class. If you need a particular import, you can bring up the context menu and select Set Imports…. Let's try something a little more complicated. Type in this snippet of code: double d = 3.14; System.out.println(d); Now select the snippet and press Ctrl+U (Run Execute) to execute it. The output will appear in the Console window. Execute is exactly like Display except that Execute doesn't show the return value (if any). You can execute loops or even call methods in your regular programs from the scrapbook page. This is useful for trying out new ideas or just for simple debugging.

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