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  1. #1
    Redefine12 is offline Member
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    Default Compare two Arrays, checking for duplication

    Good day. First post here, so please bare with me.

    I have two directories containing files. I want to output the files from directory a that are also contained in directory b.

    C:/DIFFCHECK/DIR1/: TEST_DUP.txt, TEST_UNI.txt
    C:/DIFFCHECK/DIR2/: TEST_DUP.txt, TEST2.txt

    Desired output: TEST_DUP.txt is a duplicate.

    I believe I need to use a for loop vice nested if statements, but can't get my head around this one. Please help!

    What I have so far:

    import java.io.File;

    public class diffcheck2
    {
    public static void main(String[] args)
    {
    //populate the arrays
    File f = new File("C:/DIFFCHECK/DIR1/");
    File[] rec = f.listFiles();

    File g = new File("C:/DIFFCHECK/DIR2/");
    File[] hist = g.listFiles();

    int i = 0;
    int j = 0;
    if (rec[i].isFile() && hist[j].isFile())

    if (rec[i].getName().equals(hist[j].getName())) {

    System.out.println(rec[i].getName());

    }
    }

    }

  2. #2
    JosAH's Avatar
    JosAH is online now Moderator
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    Default Re: Compare two Arrays, checking for duplication

    Don't use two arrays of file names; use two Sets instead (read the API documentation for the Set interface and its implementations).

    kind regards,

    Jos
    cenosillicaphobia: the fear for an empty beer glass

  3. #3
    farhanz2009 is offline Member
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    Default Re: Compare two Arrays, checking for duplication

    The code below shows how i would have done it. Hope it helps :)

    [ no spoonfeeding please -- mod ]
    Last edited by JosAH; 02-03-2012 at 09:27 PM.

  4. #4
    Redefine12 is offline Member
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    Default Re: Compare two Arrays, checking for duplication

    Hello JosAH. Please un-edit farhanz2009's post. I'd like to compare to code I have since written that I believe sucessfully solves the problem.
    Even with my lack of experience, I have found it is always benificial to view a problem from a different perspective. Thank you in advance :)

    My code (works):

    import java.io.File;

    public class diffcheck2
    {
    public static void main(String[] args)
    {
    //populate the arrays
    File f = new File("C:/DIFFCHECK/DIR1/");
    File[] rec = f.listFiles();

    File g = new File("C:/DIFFCHECK/DIR2/");
    File[] hist = g.listFiles();

    for(int i=0;i<rec.length;i++)
    { boolean found = false;
    for(int j=0;j<hist.length;j++){
    if((rec[i].getName().equals(hist[j].getName()))){
    found = true;
    break; } }
    if (found)
    {
    System.out.println("*Duplicate File: "+ rec[i].getName());
    }

    }
    }

    }
    Last edited by Redefine12; 02-03-2012 at 10:20 PM. Reason: Added politeness

  5. #5
    JosAH's Avatar
    JosAH is online now Moderator
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    Default Re: Compare two Arrays, checking for duplication

    We don't do any spoonfeeding in this forum; if you have tested your code and it works, you have found a solution similar to the other (spoonfeeding) reply. There's a much better way to do it though, as I suggested in my first reply: use Sets.

    kind regards,

    Jos
    cenosillicaphobia: the fear for an empty beer glass

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