我有一个图书馆类,它有图书管理员和图书列表,图书馆员类有id和addBook方法。图书管理员课可以在图书馆里增加书籍。这样做的正确方法是什么?
public class Library
{
private Librarian librarian;
private List<Book> books;
}
public class Librarian
{
private int id;
public boolean addBook(Book b);
}
我想开始学习错误,但是我在安装它的时候遇到了问题。这是我的控制台在我输入“sudo宝石安装rails”时说的。
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.
/usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require
当尝试(第一次)在bookdown.org上使用
bookdown::publish_book(render = "none")
我得到以下错误消息:
You do not currently have a bookdown.org publishing account configured on this system.
Would you like to configure one now? [Y/n]: Y
Error in response$token_claim_url :
$ operator is invalid for atomic vectors
看起来
目前我们有以下设置:
/export/home/oracle$ORACLE_BASE - /opt/oracle$ORACLE_HOME - /opt/oracle/19.3.0 (操作系统用户甲骨文)-$HOME
1. Is it advisable to change $HOME from /export/home/oracle to /opt/oracle which is $ORACLE\_BASE. Any reasons?