7: Getting Eclipse to Write Your Code Creating new template variables in Java

Generation QR in Java 7: Getting Eclipse to Write Your Code Creating new template variables

The rules governing the names of template variables aren t complicated Here s a summary: You can make up any name on the spot, as long as the name doesn t conflict with an existing name For instance, Eclipse has a pre-defined ${year} template variable If you use the name year, Eclipse inserts 2004 (or 2005, or whatever) You can make up a name, and use that name more than once in the same template pattern Eclipse keeps identically named placeholders in sync during template edit mode For instance, in Figure 7-11, if you type something in any of the counter boxes, then Eclipse copies what you type to the other two counter boxes If you make up a name, you don t have to use that name more than once in the same template pattern In Figure 7-12, I make up the name ${limit}, and I use the name only once That s just fine In template edit mode, I can tab to the limit placeholder (Refer to Figure 7-11) When I type in the limit box, Eclipse doesn t copy my typing to any other boxes You can mix and match variables in a template pattern For instance, in a particular template pattern you can use ${myFirstVar} once, use ${mySecondVar} twice, and use ${myThirdVar} ten times When you re in template edit mode, Eclipse keeps the two mySecondVar placeholders in sync with each other, and keeps all ten myThirdVar placeholders in sync with one another

Eclipse has a bunch of predefined template variables To see a list of these variables, type a dollar sign in the Pattern field of the New Template Wizard (See Figure 7-13) If, for some reason, you don t like typing dollar signs, you can get the same list by clicking the wizard s Insert Variable button

Many of Eclipse s pre-defined template variables have self-explanatory names For instance, Eclipse substitutes the name of a package in place of the ${enclosing_package} template variable In place of the ${date} template variable, Eclipse writes something like Aug 22, 2004 Some other pre-defined template variables are a little more interesting Here s a brief list: The ${cursor} template variable marks the spot where template edit mode ends For example, the do template s pattern looks like this:

do { ${line_selection}${cursor} } while (${condition});

When you type do and then press Ctrl+Space, you see the stuff in Figure 7-14 The vertical line (above the i in while) marks the place where the ${cursor} template variable lives

At first, Eclipse positions the cursor in the condition box You type a condition and then press Tab With the pressing of Tab, Eclipse moves the cursor to the little vertical line and gets ready for you to type a statement or two As soon as you start typing statements, Eclipse stops being in template edit mode A template s pattern can contain only one occurrence of the ${cursor} template variable The ${line_selection} template variable marks text that you can surround Look again at the previous example s do template If you select a bunch of statements and then press Ctrl+Space, Eclipse offers to apply the do template (See Figure 7-15) Eclipse makes this offer because of the ${line_selection} template variable in the do template s pattern If you select the do template in Figure 7-15, you get the result shown in Figure 7-16 Eclipse substitutes whatever statements you selected for the template s ${line_selection} variable

The ${word_selection} template variable marks text that you can surround Take, for instance, the <b> template:

<b>${word_selection}${}</b>${cursor}

If you select a part of a line and then press Ctrl+Space, Eclipse offers to apply the <b> template (See Figure 7-17) Eclipse makes this offer because of the ${word_selection} template variable in the <b> template s pattern The <b> template surrounds part of a line with a pair of HTML bold tags (See Figure 7-18)