Getting ArrayList Size on jsp page

Question

hi I am trying to get the total size of an arraylist but for some reason this is not being shown the code below is used to show the size.

    <%db.DBConnection db = new  db.DBConnection(); 
            ArrayList<User> myUsers =db.getAllUsers();
            %>  

   Total Subscribed Users: <p><% myUsers.size();%></p>

Thanks

Maybe this will help. http://docs.oracle.com/javaee/5/tutorial/doc/bnaov.html — Danny, Jan 18 '13 at 16:49

score 13 · Answer 1 · answered Jan 18 '13 at 17:10

13

Some of this is clearly ripe for moving out of JSP, but based on how it looks like your classes and methods are defined, this should work (JSP + JSTL):

<jsp:useBean id="db" class="db.DBConnection"/>
<c:set var="myUsers" value="${db.allUsers}"/>
Total Subscribed Users: <p>${fn:length(myUsers)}</p>

answered Jan 18 '13 at 17:10

kschneid

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thank you very much, this is exactly what I was looking for, it should be set as the correct answer. – Manuel Manhart Mar 11 '14 at 12:23
Yes I agree, using the jsp 'functions' capability is the right answer. – Jeremy Jan 19 '16 at 09:36

Kent · Answer 2 · 2013-01-20T23:33:42.123

5

does this work?

<p><%= myUsers.size()%></p>

I suggest that write as less java codes as possible in your jsp. You could consider to use some taglib, jstl. for example. Put all business codes on your server side. specially things like b.DBConnection db = new db.DBConnection();

edited Jan 20 '13 at 23:33

answered Jan 18 '13 at 16:45

Kent

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As an addition, this would be a good read: http://stackoverflow.com/a/3180202/814702 – informatik01 Jan 20 '13 at 22:48
And please remove semicolon. Quote from "Head First Servlets and JSP": **Expressions become the argument to an out.print()**. In other words, the Container takes everything you type between the `<%=` and `%>` and puts it in as the argument to a statement that prints to the implicit response `PrintWriter out`. – informatik01 Jan 20 '13 at 22:58
The valid expression is `<%= myUsers.size() %>`. Semicolon is invalid inside an expression element in a JSP page. – informatik01 Jan 20 '13 at 23:17
1

@informatik01 thank you for pointing it out. I just copy/paste his codes and added an "=". – Kent Jan 20 '13 at 23:30

score 0 · Answer 3 · answered Jan 18 '13 at 16:54

0

 int count = myUsers.size();
            %>  
            <h1>User Management</h1>
            Total Subscribed Users: <p><%=count%></p>

answered Jan 18 '13 at 16:54

Mark Fenech

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score 0 · Answer 4 · answered Jan 19 '13 at 18:45

You should do this to achieve that purpose:

Total Subscribed Users: <p><%= myUsers.size(); %></p>

Alternatively, you can also do:

Total Subscribed Users: <p><% out.print(String.valueOf(myUsers.size()));%></p>

The block of code you wrote in your question was a "scriplet". By itself, a scriptlet doesn't contribute any HTML.

See this for more details.

Getting ArrayList Size on jsp page

4 Answers4