public class StringMethod
{
    public static void main(String[] args)
    {
        String s = "This is test string";
        System.out.println("原字符串为:" + s);
        System.out.println("s.length()为：" + s.length());
        System.out.println("s.charAt(8)为:" + s.charAt(8));
        System.out.println("s.indexOf('t')为：" + s.indexOf('t'));
        System.out.println("s.lastIndex('t')为：" + s.lastIndexOf('t'));
        System.out.println("s.substring(8, 12)为：" + s.substring(8, 12) );
        System.out.println(""hello,".concat(s)为：" + "hello,".concat(s));        --------有错
        char[] chs = new char[20];
        s.getChars(8, 12, chs, 0);
        System.out.print("chs 为：");
        for (int i = 0; i < chs.length; i ++)
        {
            System.out.print(chs[i]);
        }
        System.out.println("\n End");
    }
}怎样改才能使有错那一行不改变原有意思即输出的hello是带有引号，请高手指点！！！！先谢过