Question

我有一个数据集csv文件，有大约46000个实例和17个属性..然后我提取列值并修改其值增加1现在我想要csv文件修改值。我可以得到...

     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 com.csvreader.CsvWriter;
    //import com.opencsv.CSVReader;
    //import com.opencsv.CSVWriter;
    //import au.com.bytecode.opencsv.CSVWriter;
    public class Main {

        public static void main(String[] args) {
            // TODO code application logic here        
            String filename ="bank-full.csv";

  File file= new File(filename);        
            try {           
               Scanner inputStream = new Scanner(file);
               inputStream.next();           
                 while(inputStream.hasNext())
                {
                    double abc;
                    String data= inputStream.next();                 
                    String[] values = data.split(";");
                    double balance= Double.parseDouble(values[11]);
                    balance=balance+1;                       

                           System.out.println(balance);                
                }           
                    inputStream.close();
            } catch (FileNotFoundException ex) {
                Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
            }        
                 }

Answer 1

您已在String[] values中拥有值的字符串数组。那么为什么不将修改后的balance分配给values[11]然后加入值，用分号粘贴？

您可以尝试在System.out.println(balance);之后添加此内容：

System.out.println(balance);

// replace original value with the modified balance
values[11] = String.valueOf(balance);

// iterate through the values and build a string out of them
StringBuilder sb = new StringBuilder();
for (int i = 0; i < values.length; i++) {
    sb.append(values[i]);
    if (i < values.length - 1) {
        // if it is not the last value, put a semicolon in between
        sb.append(";");
    }
}
// get the new string
String newData = sb.toString();

System.out.println(newData);

新值现在存储在字符串newData中。只需将newData写入新的.csv文件即可。

如何使用java在特定数值列值中修改后写入CSV文件

1 个答案: