我有一个CSV文件，其中包含近10000行数据。我想根据总行数将该文件拆分为10个不同的CSV文件，这样每个文件可以包含1000行数据，顺序第一个文件应该有1-1000行，第二个文件应该有1001-2000行等等上。此外，这10个不同的CSV文件中的每一个都应该只包含父CSV文件的第一列中的数据。我开发的代码将相同的数据（1.e 1-1000行）写入所有10个csv文件。我无法弄清楚代码中的错误。
for (int j=1;j<=files;j++){
String inputfile = "C:/Users/Downloads/File.csv";
BufferedReader br = new BufferedReader(new FileReader(inputfile));
FileWriter fstream1 = new FileWriter("C:/Users/Downloads/FileNumber_"+j+".csv");
BufferedWriter out = new BufferedWriter(fstream1);
String strLine = null;
for (i=i+1;i<=(j*lines);i++) { //I Have declared i as static int i = 0 and have already calculated lines and files in other part of code
strLine = br.readLine();
if (strLine!= null) {
String strar[] = strLine.split(",");
out.write(strar[0]);
if(i!=(j*lines)) {
out.newLine(); }
}
}
out.close();
答案 0 :(得分：1)
10个csv文件中每个文件中都有相同行的问题是由于myFunction方法中的下面一行
BufferedReader br = new BufferedReader(new FileReader(inputfile));
使用变量i，j，lines的逻辑非常有效。但每次调用myFunction时，br（输入文件的BufferedReader）都会再次初始化。
因此br.readLine（）将从头开始阅读。因此在10个csv文件中每个都有相同的1000行。
希望它有所帮助！
答案 1 :(得分：1)
Use this code
import java.io.*;
import java.util.Scanner;
public class csvfilesplit
{
public static void main(String[] args) throws IOException {
int split;
Scanner reader = new Scanner(System.in); // Reading from System.in
System.out.println("\n Enter The count to split each file :-----------");
int s = reader.nextInt();
File folder = new File("file/"); //*** Location of your file
int filecount = 0;
for (File fo :
folder.listFiles()) {
if (fo.isFile()) {
filecount++;}
}
System.out.println("Total source file count is :----------------------- "+filecount+"\n"); //*** Total numbr of orginal file in mentioned folder
String path = folder.getAbsolutePath();
// System.out.println("location=-----------"+path);
File[] listOfFiles = folder.listFiles();
for (int l = 0; l < listOfFiles.length; l++) {
if (listOfFiles[l].isFile()) {
System.out.println("File name Is :-------------------------- " + listOfFiles[l].getName()); //*** File name
BufferedReader bufferedReader = new BufferedReader(new FileReader(path+"/"+listOfFiles[l].getName())); // Read a souce file
String input;
int count = 0;
while((input = bufferedReader.readLine()) != null)
{
count++;
}
System.out.println("File total rows count is :-------------- "+count); //*** Number of row count in the file
split= count/s;
int n = split,z=0;
if(n!=z)
{
System.out.println("Each splitted file line count is :------ "+split+"\n"); //*** After splitted file have the rows count
FileInputStream fstream = new FileInputStream(path+"/"+listOfFiles[l].getName()); DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine;
for (int j=1;j<=s;j++)
{
File dir = new File(path+"/"+"CSV_DATA_"+j);
dir.mkdir();
File filefolder = new File(path+"/"+"CSV_DATA_"+j);
String folderpath = filefolder.getAbsolutePath();
//********Destination File Location******
FileWriter fstream1 = new FileWriter(folderpath+"/"+listOfFiles[l].getName()+".csv"); //*** Splitted files and file format(.txt/csv.....)
BufferedWriter out = new BufferedWriter(fstream1);
for (int i=1;i<=n;i++)
{
strLine = br.readLine();
if (strLine!= null)
{
out.write(strLine);
if(i!=n)
{
out.newLine();
}
}
}
out.close();
}
in.close();
}
else
{// Below N number of row in this file
System.out.println("\n******************************* Mentioned this file have below - "+s+" rows ****************************** "+listOfFiles[l].getName()+" \n");}
}
}
System.out.println("\n Splitted_CSV_files stored location is : "+path);
}
}
答案 2 :(得分：0)
请找到以下代码： -
public static void main(String[] args) throws IOException {
//first read the file
String inputfile = "C:/Users/bohrahas/Desktop/SampleCSVFile.csv";
BufferedReader br = new BufferedReader(new FileReader(inputfile));
//create thje first file which will have 1000 lines
File file = new File("C:/Users/bohrahas/Desktop/FileNumber_"+1+".csv");
FileWriter fstream1 = new FileWriter(file);
BufferedWriter out = new BufferedWriter(fstream1);
String line="";
//count the number of line
int count=1;
int file_Number=2;
while ((line = br.readLine()) != null)
{
//if the line is divided by 1000 then create a new file with file count
if(count % 1000 == 0)
{
File newFile = new File("C:/Users/bohrahas/Desktop/FileNumber_"+file_Number+".csv");
fstream1 = new FileWriter(newFile);
file_Number++;
out = new BufferedWriter(fstream1);
}
if(line.indexOf(",")!=-1)
line=line.substring(0, line.indexOf(","));
out.write(line);
out.newLine();
count++;
}
}
逻辑： -
您不必为每个循环读取父文件。只需加载一次，即创建一个对象，然后处理父文件。
在读取父线的每一行时，只需删除第一列以外的列。
答案 3 :(得分：-2)
你的逻辑非常糟糕。我为你重写了整个代码，
import java.io.*;
import java.util.Scanner;
public class FileSplit {
public static void myFunction(int lines, int files) throws FileNotFoundException, IOException{
String inputfile = "file.csv";
BufferedReader br = new BufferedReader(new FileReader(inputfile)); //reader for input file intitialized only once
String strLine = null;
for (int i=1;i<=files;i++) {
FileWriter fstream1 = new FileWriter("FileNumber_"+i+".csv"); //creating a new file writer.
BufferedWriter out = new BufferedWriter(fstream1);
for(int j=0;j<lines;j++){ //iterating the reader to read only the first few lines of the csv as defined earlier
strLine = br.readLine();
if (strLine!= null) {
String strar[] = strLine.split(",");
out.write(strar[0]); //acquring the first column
out.newLine();
}
}
out.close();
}
}
public static void main(String args[])
{
try{
int lines = 2; //set this to whatever number of lines you need in each file
int count = 0;
String inputfile = "file.csv";
File file = new File(inputfile);
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) { //counting the lines in the input file
scanner.nextLine();
count++;
}
System.out.println(count);
int files=0;
if((count%lines)==0){
files= (count/lines);
}
else{
files=(count/lines)+1;
}
System.out.println(files); //number of files that shall eb created
myFunction(lines,files);
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
}
}