如何解决当我运行 jar 文件时，我无法正确读取文件
我写了一个代码，通过读取csv文件中的信息，根据这些城市的地区创建城市和地区。 .csv 文件长 81 行。它包含来自土耳其 81 个城市的一些信息。我想将此 csv 文件中的每一行添加到一个字符串数组中，然后将其打印在屏幕上。我还想将使用此信息创建的区域对象保留在 Region 数组中。然后，我想从这个区域数组中打印区域名称。土耳其有 7 个地区。
编辑：我尝试从 txt 文件而不是 csv 读取数据。我再次遇到同样的错误。另外，我正在尝试在 Windows 上运行 jar。我在 windows(10) 上遇到这些错误，但是当我尝试在 ubuntu 上运行该程序时，却没有。
代码在 Eclipse 上看起来运行良好，并提供了我想要的输出。
我想用可执行的 jar 文件运行这个程序。所以，我通过 Eclipse 将项目导出为可运行的 jar，但是当我尝试在 cmd 上运行这个 jar 文件时，输入：
java -jar myjar.jar
我收到这样的错误。
当我用eclipse逐步运行程序时，我找不到任何可能导致错误的东西。你怎么看这个问题？
我哪里出错了？
这是我所有的类定义。
主类
import java.io.FileNotFoundException;
public class Launcher {
public static void main(String[] args) throws FileNotFoundException {
String[] infoArray = ArrayCreator.createInfoArray("Cities.csv");
for (String info : infoArray) {
System.out.println(info);
}
System.out.println();
Region[] regionArray = ArrayCreator.createRegionArray(infoArray);
for (Region region : regionArray) {
System.out.println(region.getName());
}
}
}
数组创建类
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class ArrayCreator {
private static int capacityDetector(String fileName) throws FileNotFoundException {
Scanner scanner1 = new Scanner(new File(fileName));
int count = 0;
while (scanner1.hasNext()) {
count++;
scanner1.nextLine();
}
scanner1.close();
return count;
}
public static String[] createInfoArray(String fileName) throws FileNotFoundException {
int capacity = capacityDetector(fileName);
Scanner scanner2 = new Scanner(new File(fileName));
String[] returnArray = new String[capacity];
int index = 0;
while (scanner2.hasNextLine()) {
returnArray[index] = scanner2.nextLine();
index++;
}
scanner2.close();
return returnArray;
}
/**
* This method creates an array which contains all the region.
*
* @param infoArray String array about the cities and their regions information.
* Elements must be in the CSV format and should be compatible
* with other parts of the project.
* @return an array which contains all the regions.
*/
public static Region[] createRegionArray(String[] infoArray) {
// infoArray is actually city information array. So there may be too many
// times for the same region information. We just want to create only one region
// for the same regions. So,we must do not create the regions that are already
// exist.
int index = 0;
Region[] regionArr = new Region[index + 1];
regionArr[index] = new Region(infoArray[0]); // We are sure that the region in the first information was not
// created before.
for (int i = 1; i < infoArray.length; i++) {
String info = infoArray[i];
String[] splitted_info = info.split(",");
boolean found = false;
for (Region region : regionArr) {
String newRegionName = splitted_info[3];
String currRegionName = region.getName();
if (newRegionName.equals(currRegionName)) {
found = true;
break;
}
}
if (!found) { // if the object of this region was not created before.
index++;
Region new_region = new Region(info); // We dont kNow how many regions are there and we work with
// arrays. So we have to increase the array size manually.
Region[] temp = new Region[index + 1];
for (int j = 0; j < regionArr.length; j++) {
temp[j] = regionArr[j];
}
temp[index] = new_region;
regionArr = temp;
}
}
return regionArr;
}
}
区域类
public class Region {
private int ID;
private String name;
private City[] cities;
/**
* Constructor for Region Class Object.
*
* @param name Name of the region.
*/
public Region(String info) {
String[] splitted_info = info.split(",");
this.ID = Integer.parseInt(splitted_info[2]);
this.name = splitted_info[3];
}
/**
* A helper method to find the number of the cities which are in this region.
*
* @param allCities An array which contains all the cities.
* @return An integer which is the number of the cities in this region.
*
*/
private int findCitiesOfRegionArraySize(City[] allCities) {
int returnInt = 0;
for (City aCity : allCities) {
if (aCity.getRegion().getName().equals(this.name)) {
returnInt++;
}
}
return returnInt;
}
/**
* Creates the City array of a region.
*
* @param allCities An array which contains all the cities.
* @return City array that contains all the cities in this region.
*/
public void createCitiesOfRegion(City[] allCities) {
City[] cityArray = new City[findCitiesOfRegionArraySize(allCities)];
int index = 0;
for (City aCity : allCities) {
if (aCity.getRegion().getName() == this.name) {
cityArray[index] = aCity;
index++;
}
}
this.cities = cityArray;
}
public int getID() {
return ID;
}
public String getName() {
return name;
}
public City[] getCities() {
return cities;
}
}
城市类
public class Region {
private int ID;
private String name;
private City[] cities;
/**
* Constructor for Region Class Object.
*
* @param name Name of the region.
*/
public Region(String info) {
String[] splitted_info = info.split(",");
this.ID = Integer.parseInt(splitted_info[2]);
this.name = splitted_info[3];
}
/**
* A helper method to find the number of the cities which are in this region.
*
* @param allCities An array which contains all the cities.
* @return An integer which is the number of the cities in this region.
*
*/
private int findCitiesOfRegionArraySize(City[] allCities) {
int returnInt = 0;
for (City aCity : allCities) {
if (aCity.getRegion().getName().equals(this.name)) {
returnInt++;
}
}
return returnInt;
}
/**
* Creates the City array of a region.
*
* @param allCities An array which contains all the cities.
* @return City array that contains all the cities in this region.
*/
public void createCitiesOfRegion(City[] allCities) {
City[] cityArray = new City[findCitiesOfRegionArraySize(allCities)];
int index = 0;
for (City aCity : allCities) {
if (aCity.getRegion().getName() == this.name) {
cityArray[index] = aCity;
index++;
}
}
this.cities = cityArray;
}
public int getID() {
return ID;
}
public String getName() {
return name;
}
public City[] getCities() {
return cities;
}
}
解决方法
当我使用 BufferedReader 从 CSV 文件读取数据而不是使用 Scanner 读取数据时，我的问题解决了。此外，我将必要的文件（csv 文件）用作嵌入资源，将它们放在名为资源的包中。
我用它来检测容量
private static int capacityDetector(String filename) throws IOException {
InputStream in = new FileIO().getClass().getResourceAsStream(filename);
@SuppressWarnings("resource")
BufferedReader csv = new BufferedReader(new InputStreamReader(in,StandardCharsets.UTF_8));
int capacity = 0;
@SuppressWarnings("unused")
String line;
while ((line = csv.readLine()) != null) {
capacity++;
}
return capacity;
}
代替
private static int capacityDetector(String fileName) throws FileNotFoundException {
Scanner scanner1 = new Scanner(new File(fileName));
int count = 0;
while (scanner1.hasNext()) {
count++;
scanner1.nextLine();
}
scanner1.close();
return count;
}
我用这段代码来创建信息数组
public static String[] createInfoArray(String filename) throws IOException {
InputStream in = new FileIO().getClass().getResourceAsStream(filename);
@SuppressWarnings("resource")
BufferedReader csv = new BufferedReader(new InputStreamReader(in,StandardCharsets.UTF_8));
int capacity = capacityDetector(filename);
String[] infoArray = new String[capacity];
for (int i = 0; i < capacity; i++) {
infoArray[i] = csv.readLine();
}
return infoArray;
}
代替
public static String[] createInfoArray(String fileName) throws FileNotFoundException {
int capacity = capacityDetector(fileName);
Scanner scanner2 = new Scanner(new File(fileName));
String[] returnArray = new String[capacity];
int index = 0;
while (scanner2.hasNextLine()) {
returnArray[index] = scanner2.nextLine();
index++;
}
scanner2.close();
return returnArray;
}
最后，我在 main 中调用了这些方法
String[] cityInfoArray = FileIO.createInfoArray("/resources/Cities.csv");
String[] forecastInfoArray = FileIO.createInfoArray("/resources/WeeklyForecast.csv");
现在，我可以通过双击 jar 文件毫无问题地运行我的程序。
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