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  1. #1
    dre
    dre is offline Member
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    Default Real simple code giving me trouble!

    Hi,

    I'd like to get this simple piece of code that reads an input files, adds each line to an arraylist and recognizes if a particular exists in a text file. If it does, print out the indexOf the string in the arraylist.

    Here's the code I THOUGHT would do it:


    public static void doIt(BufferedReader r, PrintWriter w) throws IOException {
    List<String> s = new ArrayList<String>();
    String line;
    int n = 0;
    while ((line = r.readLine()) != null) {
    if (line == "test")
    {
    s.add(line);
    System.out.println(s.indexOf(line));

    }


    n++;
    }

    Except when I execute the program it doesn't print anything out! I want it to print out the location of the line "test" (and it does exist in my input file) but nothing prints out and the program ends.

    I know the problem lies in the "if (line == "test")", particularily the "== "test"" part. I tested it but changing it to "if (line != null)" and the program executed perfectly.

    Any ideas as to why it's not printing out?

  2. #2
    doWhile is offline Moderator
    Join Date
    Jul 2010
    Location
    California
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    Default Re: Real simple code giving me trouble!

    When comparing String values for equality, use the equals method. == compares whether the references are equal, not necessarily the String value.

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