在JAVA中，指出下列程序运行的结果(     )

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;
    }
}