Why won't this PrintWriter populate this file?

I have a program that takes Giraffe

from a text file, creates from them ArrayList

and LinkedList

(redundantly, I know ... LinkedList

was a requirement of the second part of the assignment and I liked mine ArrayList

), sorts who their parents are, and then has to print the VBA macro to the file.

File ( D:\\Java\\Macro.txt

) is created, but it is empty. Why is nothing printed in the file? I think there is a problem with creating an array to return to the main function.

I suspect the problem is in the method GetYearGroup

in the class Herd

and how it interacts with PrintWriter

, which is on lines 51-83 of the class Main

.

Here is the code:

HW4_Name.java (main)

package giraffe;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;

public class HW4_Name {
    public static void main(String[] args) throws IOException {
        ArrayList<Giraffe> giraffes = new ArrayList<>();
        String temp[] = new String[13];
        String header = "";
        String fileLocation = "theHerd.txt";
        File textFile = new File(fileLocation);
        Scanner in = new Scanner(textFile);
        if (textFile.canRead()) {
            header = in.nextLine();
            while (in.hasNextLine()) {
                temp = in.nextLine().split("\\t", 13);
                giraffes.add(new Giraffe(temp));
                }
            }

        Herd herd = new Herd();
        for(int i = 0; i < giraffes.size(); i++){
            Giraffe g = giraffes.get(i);
            herd.Add(g);
        }
        int nGiraffes = herd.Size();
        for(int i = 0; i < nGiraffes; i++){
            Giraffe g = herd.GetAt(i);

            int nSire = g.getSireId();
            if (nSire != -1){
                g.setSire(herd.Find(nSire));
            }

            int nDam = g.getDamId();
            if (nDam != -1){
                g.setDam(herd.Find(nDam));
            }
        }
        in.close();

        PrintWriter pw = new PrintWriter("C:\\Java\\Macro.txt");
        int nHeight = 500;
        int nWidth = 900;
        int nYearHeight = nHeight / 13;
        int nRectangle = 0;
        for(int i = 0; i < 13; i++){
            int nLowYear = 50 + 5 * i;
            Giraffe[] ThisGroup = herd.GetYearGroup(nLowYear, nLowYear + 5);
            int nThisGroup = ThisGroup.length;
            int nXSpacing = nWidth / (nThisGroup + 1);
            int nYPos = 10 + nYearHeight * i;
            for(int j = 0; j < nThisGroup; j++){
                nRectangle++;
                int nXPos = 10 + nXSpacing/2 + nXSpacing * j;
                Giraffe g = ThisGroup[j];
                g.setRectangle(nRectangle);
                String strName = g.getName();
                pw.println("Call Box(" + nXPos + ", " + nYPos + ", \"" +strName + "\")");
            }
        }
        for(int i = 0; i < nGiraffes; i++){
            Giraffe g = herd.GetAt(i);
            Giraffe gSire = g.getSire();
            if (gSire != null){
                int nParentRectangle = gSire.getRectangle();
                nRectangle = g.getRectangle();
                if (nParentRectangle > 0 && nRectangle > 0){
                    pw.println("Call DadLine(" + nParentRectangle + ", " + nRectangle + ")");
                }
            }
            Giraffe gDam = g.getDam();
            if(gDam != null){
                int nParentRectangle = gDam.getRectangle();
                if (nParentRectangle > 0 && nRectangle > 0){
                    pw.println("Call MomLine(" + nParentRectangle + ", " + nRectangle + ")");
                }
            }
        }
        pw.close();
    }
}

      

Giraffe.java

package giraffe;
import java.util.ArrayList;

public class Giraffe extends Object {

    private String birthLocation, subSpecies, zoo, city, state, event, name,
    localId, sex, eachGiraffe;
    private int gId, birthYear, sireId, damId, gRectangle;
    private Giraffe gSire, gDam;

    public Giraffe(String array[]){
        this.sex = String.format("%-1s",array[1]);
        this.birthLocation = String.format("%-12s",array[5]);
        this.localId = String.format("%-7s",array[6]);
        this.name = String.format("%-20s",array[7]);
        this.subSpecies = String.format("%-14s",array[8]);
        this.zoo = String.format("%-35s",array[9]);
        this.city = String.format("%-17s",array[10]);
        this.state = String.format("%-13s",array[11]);
        this.event = String.format("%-7s",array[12]);
        this.gId = Integer.parseInt(array[0]);
        this.birthYear = Integer.parseInt(array[2].substring(0,4));

        if(array[3].equals("WILD") || array[3].equals("UNK")){
            this.sireId = -1;
        }
        else{
            this.sireId = Integer.parseInt(array[3]);
        }

        if(array[4].equals("WILD") || array[4].equals("UNK")){
            this.damId = -1;
        }
        else{
            this.damId = Integer.parseInt(array[4]);
        }
    }
    public String getName(){
        return this.name;
    }
    public int getId(){
        return gId;
    }
    public int getBirthYear(){
        return birthYear;
    }
    public int getSireId(){
        return sireId;
    }
    public int getDamId(){
        return damId;
    }
    public Giraffe getSire(){
        return gSire;
    }
    public int getRectangle(){
        return gRectangle;
    }
    public Giraffe getDam(){
        return gDam;
    }
    public void setSire(Giraffe nSire){
        this.gSire = nSire;
    }
    public void setDam(Giraffe nDam){
        this.gDam = nDam;
    }
    public void setRectangle(int nRectangle){
        this.gRectangle = nRectangle;
    }
    public String toString(){
        eachGiraffe = ("" + this.gId);
        return eachGiraffe;
    }
}

      

Herd.java

package giraffe;

public class Herd extends LinkedList{
    public Herd(){
    }
    public void Add(Giraffe g){
        InsertRight(g);
    }
    public Giraffe Find(int idNumber){
        Giraffe g = null;
        Node currNode = start;
        while(currNode != null && currNode.o.getId() != idNumber){
            currNode = currNode.next;
        }
        if(currNode.o.getId() == idNumber){
            g = currNode.o;
        }
        return g;
    }
    public Giraffe GetAt(int nIndex){
        Giraffe g = null;
        Node currNode = start;
        for(int i = 0; i < nIndex; i++){
            if(currNode != null){
                currNode = currNode.next;
            }
        }
        g = currNode.o;
        return g;
    }
    public Giraffe[] GetYearGroup(int nBegin, int nEnd){
        int nGiraffes = Size();
        int nInGroup = 0;
        for(int i = 0; i < nGiraffes; i++){
            Giraffe g = GetAt(i);
            int nBirthYear = g.getBirthYear();
            if (nBegin <= nBirthYear && nBirthYear < nEnd){
                nInGroup++;
            }
        }
        Giraffe[] gary = new Giraffe[nInGroup];
        nInGroup = 0;
        for(int i = 0; i < nGiraffes; i ++){
            Giraffe g = GetAt(i);
            int nBirthYear = g.getBirthYear();
            if(nBegin <= nBirthYear && nBirthYear < nEnd){
                gary[nInGroup] = g;
                nInGroup++;
            }
        }
        return gary;
    }
}

      

LinkedList.java

package giraffe;

public class LinkedList {
    protected Node start;
    private int errorReturn;
    public LinkedList(){
        start = null;
    }
    public LinkedList(int errorValue){
        start = null;
        errorReturn = errorValue;
        System.out.println(errorReturn);
    }
    public boolean isEmpty(){
        return (start == null);
    }
    public void InsertRight(Giraffe data){
        Node currNode;
        if (start == null){
            start = new Node(data,start);
        }
        else{
            currNode = start;
            while (currNode.next != null){
                currNode = currNode.next;
            }
            currNode.next = new Node (data, null);
        }
    }
    public int Size(){
        int length = 0;
        Node currNode = start;

        while(currNode != null){
            length++;
            currNode = currNode.next;
        }
        return length;
    }
    public void Display(){
        Node currNode = start;
        System.out.println("List contents: ");

        while (currNode != null){
            currNode = currNode.next;
        }
        System.out.println("--------------------------");
    }
}

      

Node.java

package giraffe;

public class Node {
    Giraffe o;
    Node next;

    public Node(Giraffe giraffe, Node nextNode){
        o = giraffe;
        next = nextNode;
    }
}

      

Decision

Thanks to durron597 for pointing out that BirthYear was not comparable to GetYearGroup.

Replacement:

for(int i = 0; i < 13; i++){
        int nLowYear = 50 + 5 * i;

      

Through:

for(int i = 0; i < 13; i++){
    int nLowYear = 1950 + 5 * i;

      

The problem has been fixed.

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1 answer


I see two problems, each of which can lead to what you see:

  • You are listing into a directory C:\\Java\\Macro.txt

    , but you are using a relative path to search theHerd.txt

    . Try changing your file theHerd.txt

    to an absolute path, or use Class.getResourceAsStream()

    if the file is in your classpath.
    • Use the debugger to see what objects Giraffe

      are being created at all
  • Checking your birth year seems odd:

    for(int i = 0; i < 13; i++){
        int nLowYear = 50 + 5 * i;
        Giraffe[] ThisGroup = herd.GetYearGroup(nLowYear, nLowYear + 5);
    
          

    • This only checks for years in the range 50, 55, up to 115. However, in your class, Giraffe

      you do this:

      this.birthYear = Integer.parseInt(array[2].substring(0,4));
      
            

      This will work (i.e. not throw an exception ArrayIndexOutOfBounds

      ) for four digit dates, none of which are in the 50-115 range. However, if you set your year to a value like 0073

      (you must put leading zeros), then your program will print results like Call Box(235, 162, "GiraffeName ")

      . You probably want to change this value 50

      to 1950

      .




There are other code smells in your program; I suggest reading things like (in ascending order of time):

But those two bits of code should get started.

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