在 Java 中将数据从 CSV 解析为数组
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Parsing Data from CSV to Array in Java
提问by Roger Chen
I'm trying to import a CSV file into an array that I can use within a Java program. The CSV file has successfully imported itself and the output appears on Terminal but it throws the error:
我正在尝试将一个 CSV 文件导入到我可以在 Java 程序中使用的数组中。CSV 文件已成功导入，输出显示在终端上，但会引发错误：
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at CompareCSV.main(CompareCSV.java:19)
at the end. In addition, when I try to call up elements in the array, it also shows the same error. My code is below:
在末尾。此外，当我尝试调用数组中的元素时，它也显示相同的错误。我的代码如下：
import java.io.*;
import java.util.*;
public class CompareCSV {
public static void main(String[] args) {
String fileName = "sampledata1.csv";
try {
BufferedReader br = new BufferedReader( new FileReader(fileName));
String strLine = null;
StringTokenizer st = null;
int lineNumber = 0, tokenNumber = 0;
while((fileName = br.readLine()) != null) {
lineNumber++;
String[] result = fileName.split(",");
for (int x=0; x<result.length; x++) {
System.out.println(result[x]);
}
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
采纳答案by Mathias Schwarz
You are much better off using a proper CSV parser than hacking a faulty one up yourself: http://opencsv.sourceforge.net/
使用适当的 CSV 解析器比自己破解一个有问题的解析器要好得多：http: //opencsv.sourceforge.net/
CSV is not the simple format one might be let to think (yes, a line can contain a ,that does not separate two pieces of data).
CSV 不是人们可能会想到的简单格式（是的，一行可以包含,不分隔两条数据的 a）。
回答by Andreas Dolk
Looks like your assumption, that a line in the file alwayshas three columns isn't true for all lines. Replace the for loop statement with the following line to eliminate the exception and see, why it happend:
看起来像您的假设，即文件中的一行始终包含三列并不适用于所有行。用以下行替换 for 循环语句以消除异常并查看它发生的原因：
for (int x=0; x<result.length; x++)
回答by Rao's
This is the answer for above Question
这是上述问题的答案
public class Readline {
/**
* @param args
*/
public static void main(String[] args) {
String fileName = "C:/Users/karthikrao/Desktop/cvsFile.csv";
ArrayList<Integer> margins = new ArrayList<Integer>();
BufferedReader br;
String line, token;
int i;
try {
br = new BufferedReader(new FileReader(fileName));
try {
while ((line = br.readLine()) != null) {
StringTokenizer st = new StringTokenizer(line, ",\"");
i = 0;
while (st.hasMoreTokens()) {
token = st.nextToken();
if (margins.size() <= i) {
margins.add((Integer) token.length());
} else {
margins.set(
i,
Math.max(margins.get(i),
(Integer) token.length()));
}
i++;
}
}
br = new BufferedReader(new FileReader(fileName));
while ((line = br.readLine()) != null) {
StringTokenizer st = new StringTokenizer(line, ",\"");
i = 0;
while (st.hasMoreTokens()) {
token = st.nextToken();
System.out.print(token);
for (int j = 0; j < margins.get(i) - token.length(); j++) {
System.out.print(" ");
}
System.out.print("|");
i++;
}
System.out.println();
}
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
}
回答by xiaolei yu
I suggest you not re-inventing wheel when there are so many great libraries out there. Try the uniVocity-parserswith the following code snippt as reference:
我建议你不要在有这么多伟大的图书馆时重新发明轮子。尝试使用以下代码片段作为参考的uniVocity 解析器：
public static void main(String[] args) throws FileNotFoundException {
/**
* ---------------------------------------
* Read CSV rows into 2-dimensional array
* ---------------------------------------
*/
// 1st, creates a CSV parser with the configs
CsvParser parser = new CsvParser(new CsvParserSettings());
// 2nd, parses all rows from the CSV file into a 2-dimensional array
List<String[]> resolvedData = parser.parseAll(new FileReader("/examples/example.csv"));
// 3rd, process the 2-dimensional array with business logic
// ......
}
As you can see, only 2 lines required to finish the task of parsing csv data into array. Additionally, the library provides full list of features in parsing CSV data with excellent performance.
如您所见，只需 2 行即可完成将 csv 数据解析为数组的任务。此外，该库还提供了以出色性能解析 CSV 数据的完整功能列表。
