StringBuffer输出

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; 
}
}

输出结果：

AB,B