大名鼎鼎的java动态脚本语言。已经通过了sun的认证

				class SafeNavigationTest extends GroovyTestCase {								    void testNullNavigation() {				        def x = null				        def y = x?.bar								        assert y == null				    }								    void testNormalPropertyNavigation() {				        def x = ['a':456, 'foo':['bar':123, 'x':456], 'z':99]				        				        def y = x?.foo?.bar				        				        println("found y ${x?.foo?.bar}")				        				        assert y == 123				    }								    void testNullPropertyNavigation() {				        def x = null				        				        def y = x?.foo?.bar				        				        assert y == null												        def java.awt.Color color = null				        def a = color?.alpha				        assert a == null								    }				    				    void testNormalMethodCall() {				        def x = 1234				        				        def y = x?.toString()				        				        assert y == "1234"				    }								    void testNullMethodCall() {				        def x = null				        				        def y = x?.toString()				        				        assert y == null				    }								}