String面试题

public class TestThread01 {
    String str = new String("good");
    char[] ch = {'t','e','s','t'};
    void change(String str,char[] ch){
        str = "test ok";
        ch[0] = 'b';
    }
    public static void main(String[] args) {
        TestThread01 testThread01 = new TestThread01();
        testThread01.change(testThread01.str, testThread01.ch);
        System.out.println(testThread01.str);//good
        System.out.println(testThread01.ch);//best
    }
}