我正在使用一个大型数据集的大型csv文件,大约有17个属性和大约40000行。我想以相反的顺序写出每行值的第i个位置(第一行ith“,”分隔值替换为40000 ith“,”分开...第二个替换为39999 ...同样全部)(这里我提取了第12个值) = ith)。我可以这样做请帮助我。!!
package demo;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.io.FileWriter;
import java.io.*;
/**
*
/**
*
* @author admin
*/
public class Demo {
/**
* @param args the command line arguments
*/
public static void main(String[] args)throws IOException {
String filename = "bank-full.csv";
File file = new File(filename);
BufferedWriter writer = null;
try {
writer = new BufferedWriter(new FileWriter("bank-full_updated.csv"));
}
catch (IOException e) {
}
try {
Scanner inputStream = new Scanner(file);
inputStream.next();
double Tuple;
int count=0;
Tuple = 0;
while (inputStream.hasNext())
{
String data = inputStream.next();
String[] values = data.split(";");
double balance = Double.parseDouble(values[11]);
//balance=balance+1;
values[11] = String.valueOf(balance);
count=count+1;
// iterate through the values and build a string out of them
StringBuilder sb = new StringBuilder();
// String newData = sb.toString();
for (int i = 0; i < values.length; i++) {
sb.append(values[i]);
if (i < values.length - 1) {
sb.append(";");
}
}
// get the new string
System.out.println(sb.toString());
writer.write(sb.toString()+"\n");
}
writer.close();
inputStream.close();
} catch (FileNotFoundException ex) {
Logger.getLogger(Demo.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
答案 0 :(得分:0)
不确定您为什么要这样做,但听起来您需要将文件读入Collection(例如ArrayList),将每行添加为记录,然后从末尾循环遍历列表开始 - 并将所有内容打印回(新)文件......