一道面试题

题目的代码大致如下：

public class StringTest {
    
    public static void process(String str){
        str="A";
    }
    
    public static void process(StringBuffer sb){
        sb=new StringBuffer("A");
        sb.append("a");
    }
    
    public static void process(String str,StringBuffer sb){
        
        sb.append("a");
    }
    
    public static void main(String[] args) {
        String str="a";
        StringBuffer sb=new StringBuffer("a");
        process(str);
        System.out.println(str);
        process(sb);
        System.out.println(sb);
        process(str,sb);
        System.out.println(sb);
    }
}

猜想输出结果和实际运行一致：

a
a
aa