StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
18994834
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2013-09-25T01:40:13.363
FavoriteCount
0
LastActivityDate
2013-09-25T01:40:13.363
LastEditDate
LastEditorUserId
0
OwnerUserId
535871
ParentId
18994774
PostTypeId
2
Score
3
ViewCount
0
LastEditorDisplayName
text
Body
There are a couple of problems with your code: <ol> <li><code>main</code> is a <code>static</code> method, meaning that it executes outside the context of any instance of <code>Library</code>. However, <code>s</code> is an instance field of <code>Library</code>. You should either make <code>s</code> a <code>static</code> field or create an instance of <code>Library</code> and reference the field through that instance: <pre><code>public static void main(String[] args) { Library lib = new Library(); . . . lib.addStudent(g); // etc. } </code></pre></li> <li><code>addStudent</code> is not a member function of <code>ArrayList</code>; it is a member function of <code>Library</code>. Thus, you should not be coding <code>s.addStudent(f);</code>, etc.</li> <li>You don't initialize <code>s</code>, so the first time your code tries to add an element, you will get a <code>NullPointerException</code>. You should initialize it either inline: <pre><code>private ArrayList<Student> s = new ArrayList<Student>(); </code></pre> or write a constructor for <code>Library</code> and initialize the field there.</li> <li>Your latest change—to add <code>private ArrayList<Student> s;</code> to the <code>Student</code> class—is on the wrong track. You will end up with a separate list of students for each student you create; surely not what you want! The list of students belongs with the <code>Library</code> where it was.</li> <li>Your constructor for <code>Student</code> looks like it has the assignments backwards.</li> </ol>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POHow do I add my elements to my arraylist?
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USTed Hopp
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POHow do I add my elements to my arraylist?
 singulars
 PostTypePostTypeId
 PTQuestion
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.