Perplexing problem with inserting into a LinkedList Object

From: privacy.at Anonymous Remailer (mixmaster_at_remailer.privacy.at)
Date: 05/22/04

  • Next message: precious: "Re: Block Cipher in Java" 
    Date: Sat, 22 May 2004 07:19:41 +0200 (CEST)

    O great java gurus I conjure thee from the abyss
    in the hopes that your combined wisdom can figure out this
    problem.

    I'm trying to build a list of lists; each object of class Bomlist
    is an object of class Assynode, which in turn consists of a string
    and two LinkedLists.

    But I'm having trouble just populating Bomlist - this program executes
    fine when Collections.binarySearch is called only once (for "B"). But
    when lines 46-55 are uncommented so that "A" is attempted to be inserted
    the program fails.

    In the real app, inLine will be supplied by reading from a file.

    TIA,

    Steve

    //----Bomlist.java-------------------------------------------------------
    // Bomlist application - not an applet
    import java.util.*;
    import java.io.*;
    import javax.swing.*;
    import javax.swing.event.*;

    public class Bomlist {
        private LinkedList bom_list;
            
        public Bomlist() {
            System.out.println("inside Bomlist constructor");
            bom_list = new LinkedList();
            readRecords();
            printList();
        }

        private void readRecords() {
            int indx_cur;
            int indx_nha;
            int indx_tmp;
            System.out.println("inside readRecords");

            StringTokenizer tokenizer;
            Vector rows = new Vector(3);

            int num_tokens = 0, ii =0;
            String inLine, aaa, bbb, ccc;
            inLine = "B;A;A001";
            String strarry[] = new String[3]; // edgelist only contains three fields

                    tokenizer = new StringTokenizer( inLine,";");
                    num_tokens = tokenizer.countTokens();
                    for( ii = 0; ii < num_tokens ; ii++ ) { //loop to get all the elements of line
                        strarry[ii] = tokenizer.nextToken();
                    }
                    //find current and insert if nessary
                    indx_cur = Collections.binarySearch(bom_list, strarry[0]);
                    System.out.println(strarry[0] + " -- indx_cur=" + indx_cur);
                    System.out.println("got to 1");
                    if( indx_cur < 0 ) {
                        System.out.println("got to 2a");
                        Assynode curnode = new Assynode( strarry[0]);
                        insertOrdered(curnode);
                    }
    // why does the program fail when this section is included???
    /*
                    indx_nha = Collections.binarySearch(bom_list, strarry[1]);
                    System.out.println(strarry[1] + " -- indx_nha=" + indx_nha);
                    System.out.println("got to 3");
                    if( indx_nha < 0 ) {
                        System.out.println("got to 3a");
                        Assynode nhanode = new Assynode( strarry[1]);
                        insertOrdered(nhanode);
                    }
    */
        }

        public void printList() {
           String build_str = "";
           System.out.println("should be in printList");
           ListIterator lili = bom_list.listIterator();
           while (lili.hasNext()) {
               Assynode current = (Assynode) lili.next();
               current.printAssy();
           }
        }

        public void insertOrdered( Object newobj) {
           Assynode screw = (Assynode) newobj;
           System.out.println("got inside insertORdered for part - " + screw.partno);
           ListIterator li = bom_list.listIterator(); // sets pointer at BEGINNING of list
           while (li.hasNext()) {
              Assynode current = (Assynode) li.next();
              if( current.compareTo(newobj) > 0 ) {
                  li.previous();
                  break;
              }
           }
           li.add( newobj);
        }

        public static void main( String args[] ) {
            System.out.println("inside main");
            final Bomlist bom = new Bomlist();
            System.exit( 0 );
        }
    }

    class Assynode implements Comparable {
        public String partno;
        public LinkedList nha_list;
        public LinkedList sub_list;

        public Assynode( String aa) {
            System.out.println(" inside default Assynode constructor");
            partno = aa;
            LinkedList nha_list = new LinkedList();
            LinkedList sub_list = new LinkedList();
        }

        public Assynode( String aa, String bb, String cc) {
            partno = aa;
            LinkedList nha_list = new LinkedList();
            nha_list.add( bb);
            LinkedList sub_list = new LinkedList();
            sub_list.add( cc);
        }

        public int compareTo( Object other) {
            System.out.println(" inside custom Assynode compareTo");
            Assynode ddd = (Assynode) other; // <-- fails here on SECOND call!!
            System.out.println(" got to compareTo-a");
            int compare = this.partno.compareTo( ddd.partno);
            System.out.println(" got to compareTo-b");
            String outmsg = " " + this.partno + " compared to " + ddd.partno + " returns " + compare;
            System.out.println(outmsg);
            return compare;
            // the returned int is negative if this.partno is less than other.partno
            // the returned int is zero if this.partno is equal to other.partno
            // the returned int is positive if this.partno is more than other.partno
        }

        public boolean equals( Object other) {
            Assynode fff = (Assynode) other;
            boolean isequal = this.partno.equals( fff.partno);
            return isequal;
        }

        public void printAssy() {
           System.out.println("----------------");
           System.out.println(partno);
        }
    }
    //----end of Bomlist.java-------------------------------------------------------

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