下列程序段执行后，运行结果为1 。
public class Foo {
public static void main (String [] args) {
StringBuffer a = new StringBuffer (“A”);
StringBuffer b = new StringBuffer (“B”);
operate(a,b);
System.out.printIn(a + “,” +b);
}
static void operate (StringBuffer x, StringBuffer y) {
x.append(y);
y = x;
}
}
