以下代码正确的执行结果是( )。 class A { private int i = 10; public void printI() { System.out.print(i); } } class B extends A { private int i = 20; public void printI() { System.out.print(i); } } public class Test { public static void main(String args[]) { B b = new B(); A a = b; b.printI(); a.printI(); } }