JAVA值传递

看见一道笔试题：

public class Example {    String str = new String("good");    char[] ch = { 'a', 'b', 'c' };    public static void main(String args[]) {        Example ex = new Example();        ex.change(ex.str, ex.ch);        System.out.print(ex.str + " and ");        System.out.print(ex.ch);    }    public void change(String str, char ch[]) {        str = "test ok";        ch[0] = 'g';    }}