CODEWITHSUNDEEP
javajakarta-ee
Student
Student

Reputation: 387

readLine for reading multiple lines without a loop?

So my servlet is reading a url link from another servlet and then publishing the article associated with it. All the articles are in a single .txt file with each article on its own separate line. So I have made the first URL link work properly but I can't get the 2nd to work properly. The problem is if I use a loop like while( br.readline() != null) then it will display all 3 articles instead of just the article whos URL I clicked on. When I don't loop it and just use br.readline() it stops at the first line and doesn't move to the second line like I need it to if I'm asking for URL 2 or URL 3. Here is my code:

s = br.readLine();
    out.println("<tr>");
    StringTokenizer s2 = new StringTokenizer(s, "|");
    if (request.getParameter("article1") != null){
        while (s2.hasMoreElements()){
            if (index == 0){
                out.println("<td class='first'>"+s2.nextElement()+"</td>");
            }
            else if (index == 1){
                out.println("<td>"+s2.nextElement()+"</td>");
            }
            else if (index == 2){
                out.println("<td>"+s2.nextElement()+"</td>");
            }
            else if (index == 3){
                out.println("<td>"+s2.nextElement()+"</td>");
            }
            index++;
            out.println("</tr>");
        }
    }
    else if (request.getParameter("article2") != null){
    s = br.readLine();
        while (s2.hasMoreElements()){
            if (index == 4{
                out.println("<td class='first'>"+s2.nextElement()+"</td>");
            }
            else if (index == 5){
                out.println("<td>"+s2.nextElement()+"</td>");
            }
            else if (index == 6){
                out.println("<td>"+s2.nextElement()+"</td>");
            }
            else if (index == 7){
                out.println("<td>"+s2.nextElement()+"</td>");
            }
            index ++;
            out.println("</tr>");
        }

I know this is probably just a stupid coding error that I can't see because I've been looking at it for so long, but I can't seem to get it to do what I want it to. Also I didn't show the article 3 code because it is essentially the same, and if I can fix article 2's code, then article 3's will basically be the same.

Upvotes: 1

Views: 139

Answers (3)

eldjon
eldjon

Reputation: 2840

Apart from the suggestions above, i want to add that if you are using a buffered reader and you know the line you want to read, you may want to add a counter so you can keep track of the number of line you are currently at and exit the loop whenever you are done. Pretty much sth like this: 

int wantedLineNr = 4;
String currentLine = null;
int lineCounter = 0;
while ((currentLine = br.readLine()) != null) { 

    lineCounter ++;
    if(lineCounter == wantedLineNr){

       // the line is reached so execute the necessary code and exit the loop
       break;
    }
}

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1500675

I would strongly advise you to separate out the "reading the data" from the "outputting HTML" sections of your code.

It looks like you should create a data structure for an article, with properties for whatever the different bits in each line are. You can then:

  • Create a List<Article>
  • Read a line at a time
    • Parse the line as an Article (e.g. via splitting as per your code)
    • Add each Article to the list

You now have a List<Article> which you can use in any way you like in the part of your code which needs to output HTML. You don't need to worry about mixing the line-reading and parsing with the output code. This should make it all much simpler to handle.

Upvotes: 2

folkol
folkol

Reputation: 4883

I do not think that this is a pretty way of doing things, but if you just want to get this done, call br.readLine inside the if blocks instead, when you know how many lines you have to discard.

Upvotes: 0

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