为什么下面的代码打印“1”？classA{intx=1;}classBextendsA{intx=2;}classBase{AgetObject(){System.out.println("Base");returnnewB();}}publicclassCovariantReturnextendsBase{BgetObject(){System.out.println("CovariantReturn");returnnewB();}/***@paramargs*/publicstaticvoidmain(String[]args){Basetest=newCovariantRetu