Java™ Application Development on Linux - Dator

224Chapter 9Ant: An IntroductionnameThe name of the target. This is the name entered as an argument to ant.This is also the name that may be used in the default attribute of theproject tag.unlessThis is the reverse of the if attribute. The target is built unless theproperty is set.9.4.2.3 PropertiesThere is more than one way to set what we might call variables in ant. Theonly one we will concern ourselves with here is properties. Properties are like asimple hash, or associative array. They associate value, which is stored as aString, with a name, which is also a String. They behave very much like theProperties class introduced earlier in this book. 7 You can use buildfile propertiesto associate a single name with a single value that you use in multipleplaces throughout the buildfile to make configuration changes easier and lesserror-prone. Some tasks also expect certain properties to be set, as we shallsoon see.You set a property with the property tag (Example 9.2).Example 9.2 A useless build.xml example to demonstrate propertiesThis example's usefulness:${example.utility}. OK?Running ant with Example 9.2 gives this output:7. In fact, an examination of the ant source code reveals that ant properties are stored in aHashTable.