執(zhí)行以下程序后的輸出結果是（）。
public class Test {
public static void main(String[] args) {
StringBuffer a = new StringBuffer(“A”);
StringBuffer b = new StringBuffer(“B”);
operator(a, b);
System.out.println(a + “,” + b);
}
public static void operator(StringBuffer x, StringBuffer y) {
x.append(y); y = x;
}
}