反射突破String不可变

try
{
    String str = "yyg";
    System.out.println("str=" + str + ", 唯一性hash值=" + System.identityHashCode(str));
    Class stringClass = str.getClass();
    //获取String类中的value属性
    Field field = stringClass.getDeclaredField("value");
    //设置私有成员的可访问性,进行暴力反射
    field.setAccessible(true);
    //获取value数组中的内容
    char[] value = (char[]) field.get(str);
    System.out.println("value=" + Arrays.toString(value));
    value[1] = 'z';
    System.out.println("str=" + str + ", 唯一性hash值=" + System.identityHashCode(str));
}
catch(NoSuchFieldException | IllegalAccessException e)
{
    e.printStackTrace();
}