【2016Java面试题】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; 

}

}

• A.A,A

• B.A,B

• C.B,B

• D.AB,B