以下 JAVA 代码，Test 执行时的输出结果是__?

class A
{
    public void printValue()
    {
        System.out.print("A");
    }
}

class S extends A
{
    public void printValue()
    {
        System.out.print("S");
    }
}

public class Test
{
    public static void main(String[] args)
    {
        S s = new S();
        s.printValue();
        A as = (A)s;
        as.printValue();
        as = new A();
        as.printValue();
    }
}