How to use Linked lists and classes......


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Thread: How to use Linked lists and classes......

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  1. #1
    Brent Guest

    How to use Linked lists and classes......


    I was hoping someone could help me with this...I am trying to access methods
    of a instance of a class that is stored in the LinkedList object. I can
    print out the reference to the object stored in the linked list, but I can't
    get to the methods. I have looked at List Iterator in the instance of my
    linked list, but am not real sure on how to use it, nor can I find any real
    good documentation on it. It also won't let me directly access the element
    index using list.size or any of its methods. The code follows...Someone please
    help and thanks for any help.

    import java.io.*;
    import java.util.*;

    public class infile
    {
    public static void main(String [] argv) throws FileNotFoundException
    {
    String line;

    LinkedList list = new LinkedList();
    FileReader fr = null;
    BufferedReader infile = null;
    StringTokenizer t;

    fr = new FileReader("fds.txt");

    if(fr != null)
    {
    infile = new BufferedReader(fr);

    if(infile == null)
    {
    System.out.println("Changing to BufferedReader failed");
    System.exit(0);
    }
    }
    else
    {
    System.out.println("File not found");
    System.exit(0);
    }

    try
    {
    while((line = infile.readLine()) != null)
    {
    t = new StringTokenizer(line,">");

    DbTemplate myFD = new DbTemplate();

    String str = t.nextToken();
    myFD.setLeftSide(str);
    System.out.println(myFD.getLeftSide() );

    str = t.nextToken();
    myFD.setRightSide(str);
    System.out.println(myFD.getRightSide() );

    myFD.setfD();
    System.out.println(myFD.getFD() );

    list.add(myFD);


    }//while end

    }

    catch(IOException e)
    {
    System.err.println("End of File");
    }



    System.out.println( "\nlist: " );
    for ( int k = 0; k < list.size(); k++ )
    {
    System.out.print( list.get( k ) + " " );
    k.getFD(); // ERROR about int can't be dereferenced
    *******I want to print out the leftSide, rightSide, and myFD of class DbTemplate
    right here. Thats all.*********

    }




    }//main end
    }//Class end

    class DbTemplate
    {
    private String fD, leftSide, rightSide, oldFD;

    public void setfD()
    {
    fD = getLeftSide() + ">" + getRightSide();
    }

    public String getFD()
    {
    return fD;
    }

    public void setLeftSide(String x)
    {
    leftSide = x;
    }

    public String getLeftSide()
    {
    return leftSide;
    }

    public void setRightSide(String x)
    {
    rightSide = x;
    }

    public String getRightSide()
    {
    return rightSide;
    }
    }

  2. #2
    Paul Clapham Guest

    Re: How to use Linked lists and classes......

    > System.out.print( list.get( k ) + " " );
    > k.getFD(); // ERROR about int can't be dereferenced
    > *******I want to print out the leftSide, rightSide, and myFD of class

    DbTemplate
    > right here. Thats all.*********


    list.get(k) returns an Object. You have to cast its result to DBTemplate if
    you want to use it as such, e.g. "DBTemplate temp =
    (DBTemplate)list.get(k);".

    "k.getFD()" is in error because you declared "k" to be an int, which is a
    primitive value and doesn't have any methods, let alone a getFD() method.

    PC2

    Brent <bqlauer@swbell.net> wrote in message news:39f339ed$1@news.devx.com...
    >
    > I was hoping someone could help me with this...I am trying to access

    methods
    > of a instance of a class that is stored in the LinkedList object. I can
    > print out the reference to the object stored in the linked list, but I

    can't
    > get to the methods. I have looked at List Iterator in the instance of my
    > linked list, but am not real sure on how to use it, nor can I find any

    real
    > good documentation on it. It also won't let me directly access the

    element
    > index using list.size or any of its methods. The code follows...Someone

    please
    > help and thanks for any help.
    >
    > import java.io.*;
    > import java.util.*;
    >
    > public class infile
    > {
    > public static void main(String [] argv) throws FileNotFoundException
    > {
    > String line;
    >
    > LinkedList list = new LinkedList();
    > FileReader fr = null;
    > BufferedReader infile = null;
    > StringTokenizer t;
    >
    > fr = new FileReader("fds.txt");
    >
    > if(fr != null)
    > {
    > infile = new BufferedReader(fr);
    >
    > if(infile == null)
    > {
    > System.out.println("Changing to BufferedReader failed");
    > System.exit(0);
    > }
    > }
    > else
    > {
    > System.out.println("File not found");
    > System.exit(0);
    > }
    >
    > try
    > {
    > while((line = infile.readLine()) != null)
    > {
    > t = new StringTokenizer(line,">");
    >
    > DbTemplate myFD = new DbTemplate();
    >
    > String str = t.nextToken();
    > myFD.setLeftSide(str);
    > System.out.println(myFD.getLeftSide() );
    >
    > str = t.nextToken();
    > myFD.setRightSide(str);
    > System.out.println(myFD.getRightSide() );
    >
    > myFD.setfD();
    > System.out.println(myFD.getFD() );
    >
    > list.add(myFD);
    >
    >
    > }//while end
    >
    > }
    >
    > catch(IOException e)
    > {
    > System.err.println("End of File");
    > }
    >
    >
    >
    > System.out.println( "\nlist: " );
    > for ( int k = 0; k < list.size(); k++ )
    > {
    > System.out.print( list.get( k ) + " " );
    > k.getFD(); // ERROR about int can't be dereferenced
    > *******I want to print out the leftSide, rightSide, and myFD of class

    DbTemplate
    > right here. Thats all.*********
    >
    > }
    >
    >
    >
    >
    > }//main end
    > }//Class end
    >
    > class DbTemplate
    > {
    > private String fD, leftSide, rightSide, oldFD;
    >
    > public void setfD()
    > {
    > fD = getLeftSide() + ">" + getRightSide();
    > }
    >
    > public String getFD()
    > {
    > return fD;
    > }
    >
    > public void setLeftSide(String x)
    > {
    > leftSide = x;
    > }
    >
    > public String getLeftSide()
    > {
    > return leftSide;
    > }
    >
    > public void setRightSide(String x)
    > {
    > rightSide = x;
    > }
    >
    > public String getRightSide()
    > {
    > return rightSide;
    > }
    > }




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