使用JAVA从CSV文件中读取列

Question

嗨,我正在尝试读取test.csv在JAVA中调用的CSV文件.以下是我的代码:

import java.io.BufferedReader;
import java.io.FileReader;

public class InsertValuesIntoTestDb {

    @SuppressWarnings("rawtypes")
    public static void main(String[] args) throws Exception {
                String splitBy = ",";
        BufferedReader br = new BufferedReader(new FileReader("test.csv"));
        String line = br.readLine();
        while(line!=null){
             String[] b = line.split(splitBy);
             System.out.println(b[0]);
        }
        br.close();

  }
}

这是我的CSV文件(test.csv):

a,f,w,b,numinst,af,ub
1RW,800,64,22,1,48:2,true
1RW,800,16,39,1,48:2,true
1RW,800,640,330,1,48:2,true
1RW,800,40,124,1,48:2,true
1RW,800,32,104,1,48:2,true
1RW,800,8,104,1,48:2,true
1R1W,800,65536,39,1,96:96,true
1R1W,800,2048,39,1,96:96,true
1R1W,800,8192,39,1,48:48,true

我试图打印csv中的第一列,但我得到的输出只是a一个无限循环.任何人都可以帮我修复此代码以打印整个第一列.谢谢.

Answer 1

如果您使用的是Java 7+,则可能需要使用NIO.2,例如:

❍ 代码:

public static void main(String[] args) throws Exception {

    File file = new File("test.csv");

    List<String> lines = Files.readAllLines(file.toPath(), 
            StandardCharsets.UTF_8);

    for (String line : lines) {
        String[] array = line.split(",", -1);
        System.out.println(array[0]);
    }

}

❍ 输出:

a
1RW
1RW
1RW
1RW
1RW
1RW
1R1W
1R1W
1R1W

Answer 2

在循环内连续读取输入,以便为变量line分配一个非初始值的值

while ((line = br.readLine()) !=null) {
  ...
}

旁白:使用诸如OpenCSV之类的 CSV库已经解决了这个问题.以下是读取和写入 CSV文件的示例

Answer 3

如果您有csv文件,则逗号分割不会一直有效

"Name" , "Job" , "Address"
"Pratiyush, Singh" , "Teacher" , "Berlin, Germany"

所以,我建议使用Apache Commons CSV API:

    Reader in = new FileReader("input1.csv");
    Iterable<CSVRecord> records = CSVFormat.EXCEL.parse(in);
    for (CSVRecord record : records) {
      System.out.println(record.get(0));
    }