我正在尝试获取一个初始CSV文件，并将其通过一个类检查另一个文件（如果该文件具有A或D），然后将其添加到数组对象或从中删除该条目。
1, Bulbasaur
2, Ivysaur
3, venasaur
A, Charizard
A, Suirtle
D, 2
话虽这么说，将新数组的内容保存到新的CSV文件时遇到了很多麻烦。我检查了数组和类文件是否正常工作。我一直在尝试并且未能将“ pokedex1”对象数组的最终内容带到新的CSV文件中。
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class PokedexManager {
public static void printArray(String[] array) {
System.out.print("Contents of array: ");
for(int i = 0; i < array.length; i++) {
if(i == array.length - 1) {
System.out.print(array[i]);
}else {
System.out.print(array[i] + ",");
}
}
System.out.println();
}
public static void main(String[] args) {
try {
//output for pokedex1 using PokemonNoGaps class
PokemonNoGaps pokedex1 = new PokemonNoGaps();
//initializes scanner to read from csv file
String pokedexFilename = "pokedex.csv";
File pokedexFile = new File(pokedexFilename);
Scanner pokescanner = new Scanner(pokedexFile);
//reads csv file, parses it into an array, and then adds new pokemon objects to Pokemon class
while(pokescanner.hasNextLine()) {
String pokeLine = pokescanner.nextLine();
String[] pokemonStringArray = pokeLine.split(", ");
int id = Integer.parseInt(pokemonStringArray[0]);
String name = pokemonStringArray[1];
Pokemon apokemon = new Pokemon(id, name);
pokedex1.add(apokemon);
}
//opens changeList.csv file to add or delete entries from Pokemon class
String changeListfilename = "changeList.csv";
File changeListFile = new File(changeListfilename);
Scanner changeScanner = new Scanner(changeListFile);
//loads text from csv file to be parsed to PokemonNoGaps class
while(changeScanner.hasNextLine()) {
String changeLine = changeScanner.nextLine();
String[] changeStringArray = changeLine.split(", ");
String action = changeStringArray[0];
String nameOrId = changeStringArray[1];
//if changList.csv file line has an "A" in the first spot add this entry to somePokemon
if(action.equals("A")) {
int newId = pokedex1.getNewId();
String name = nameOrId;
Pokemon somePokemon = new Pokemon(newId, name);
pokedex1.add(somePokemon);
}
//if it has a "D" then send it to PokemonNoGaps class to delete the entry from the array
else { //"D"
int someId = Integer.parseInt(nameOrId);
pokedex1.deleteById(someId);
}
//tests the action being taken and the update to the array
//System.out.println(action + "\t" + nameOrId + "\n");
System.out.println(pokedex1);
//*(supposedly)* prints the resulting contents of the array to a new csv file
String[] pokemonList = changeStringArray;
try {
String outputFile1 = "pokedex1.csv";
FileWriter writer1 = new FileWriter(outputFile1);
writer1.write(String.valueOf(pokemonList));
} catch (IOException e) {
System.out.println("\nError writing to Pokedex1.csv!");
e.printStackTrace();
}
}
//tests final contents of array after being passed through PokemonNoGaps class
//System.out.println(pokedex1);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
public class PokemonNoGaps implements ChangePokedex {
private Pokemon[] pokedex = new Pokemon[1];
private int numElements = 0;
private static int id = 0;
// add, delete, search
@Override
public void add(Pokemon apokemon) {
// if you have space
this.pokedex[this.numElements] = apokemon;
this.numElements++;
// if you don't have space
if(this.numElements == pokedex.length) {
Pokemon[] newPokedex = new Pokemon[ this.numElements * 2]; // create new array
for(int i = 0; i < pokedex.length; i++) { // transfer all elements from array into bigger array
newPokedex[i] = pokedex[i];
}
this.pokedex = newPokedex;
}
this.id++;
}
public int getNewId() {
return this.id + 1;
}
@Override
public void deleteById(int id) {
for(int i = 0; i < numElements; i++) {
if(pokedex[i].getId() == id) {
for(int j = i+1; j < pokedex.length; j++) {
pokedex[j-1] = pokedex[j];
}
numElements--;
pokedex[numElements] = null;
}
}
}
public Pokemon getFirstElement() {
return pokedex[0];
}
public int getNumElements() {
return numElements;
}
public String toString() {
String result = "";
for(int i = 0; i < this.numElements; i++) {
result += this.pokedex[i].toString() + "\n";
}
return result;
}
}
1, Bulbasaur
3, Venasaur
4, Charizard
5, Squirtle
我使用了错误的文件编写器吗？我是在错误的时间还是错误地致电文件编写器？换句话说，我不知道为什么我的输出文件为空并且没有加载数组内容。有人可以帮我吗？
答案 0 :(得分：0)
String outputFile1 = "pokedex1.csv";
FileWriter writer1 = new FileWriter(outputFile1);
似乎在您的while循环内，因此每次都会创建一个新文件。
使用FileWriter(File file, boolean append)构造函数或在循环之前创建
答案 1 :(得分：0)
运行此程序时，我发现了一些问题。如上一个答案所述，您想在写入新的pokedx1.csv
的代码部分中将文件append设置为true。 try {
String outputFile1 = "pokedex1.csv";
FileWriter fileWriter = new FileWriter(prefix+outputFile1, true);
BufferedWriter bw = new BufferedWriter(fileWriter);
for(String pokemon : pokedex1.toString().split("\n")) {
System.out.println(pokemon);
bw.write(pokemon);
}
bw.flush();
bw.close();
} catch (IOException e) {
System.out.println("\nError writing to Pokedex1.csv!");
e.printStackTrace();
}
我选择使用缓冲读取器作为解决方案。我发现的另一个问题是您正在阅读pokedex.csv，但文件名为pokemon.csv。
String pokedexFilename = "pokemon.csv";
我进行了上述更改以解决此问题。
在旁注中，我注意到您创建了多个扫描仪来读取两个文件。对于这些类型的资源，优良作法是在使用完这些资源后立即调用close方法。如下所示。
Scanner pokescanner = new Scanner(pokedexFile);
// Use scanner code here
// Once finished with scanner
pokescanner.close();