为什么此 PrintWriter 不填充此文件？

Question

我有一个程序，它从一个文本文件中获取 Giraffes，从中创建一个 ArrayList 和 LinkedList（冗余，我知道... LinkedList 是作业第二部分的要求，我喜欢我的 ArrayList)，找出他们的 parents 是谁，然后应该将 VBA 宏打印到文件中.

文件 (D:\Java\Macro.txt) 已创建，但未填充任何内容。 为什么没有任何内容打印到文件中？ 我认为创建 return 数组到主函数时存在问题。

我怀疑问题出在 Herd Class 中的 GetYearGroup 方法中，以及它与位于第 51 行的 PrintWriter 接口的方式-83 的 Main class.

代码如下：

HW4_Name.java（主要）

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;
    }
}

解决方案

感谢 durron597 指出 birthYear 函数与 GetYearGroup 函数不可比。

正在替换：

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

与：

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

问题已解决。

Answer 1

我看到两个问题，这两个问题都可能导致您所看到的情况：

您正在输出到 C:\Java\Macro.txt 目录，但您使用的是相对路径来查找您的 theHerd.txt。尝试将您的 theHerd.txt 文件更改为绝对路径，或者如果该文件位于您的 class 路径中，则使用 Class.getResourceAsStream()。
- 使用调试器查看是否完全创建了 Giraffe 个对象
你的出生年份检查看起来很奇怪：
```
for(int i = 0; i < 13; i++){
    int nLowYear = 50 + 5 * i;
    Giraffe[] ThisGroup = herd.GetYearGroup(nLowYear, nLowYear + 5);
```
- 这只会检查 50、55 到 115 范围内的年份。但是，在您的 Giraffe class 中，您可以这样做：
```
this.birthYear = Integer.parseInt(array[2].substring(0,4));
```
  这仅适用于 4 位数的日期年份（即不抛出 ArrayIndexOutOfBounds 异常），其中 none 在 50-115 范围内。但是，如果您将年份设置为类似 0073 的值（您必须放置前导零），那么您的程序将打印类似 Call Box(235, 162, "GiraffeName ") 的结果。 您可能想将 50 更改为 1950。

您的程序有其他代码味道；我建议阅读以下内容（按时间投入的顺序）：

但是这两段代码应该可以帮助您入门。

为什么此 PrintWriter 不填充此文件？

Why won't this PrintWriter populate this file?

java

linked-list

printwriter