一个java面试题

package com.atguigu.exer;


public class StringTest {
    String str=new String("good");
    char[] ch={'t','e','s','t'};
    public void change(String str,char ch[]){
        str="test ok";
        ch[0]='b';
    }

    public static void main(String[] args) {
        StringTest ex=new StringTest();
        ex.change(ex.str,ex.ch);
        System.out.println(ex.str); 
        System.out.println(ex.ch); 
    }
}

求输出的结果