将数据添加到 CSV 文件中的特定记录

Question

我在 CSV 文件中有一条记录，我正在尝试使用以下代码向同一特定记录添加一些额外信息（名称），但它不起作用。没有显示错误，但我尝试添加的信息没有出现。我错过了什么？

public class AddName {
public static void main(String[] args) {

    String filepath="Zoo.csv";
    String editTerm="Fish";
    String addedName="Ron";

    addToRecord(filepath,editTerm,addedName);

}
public static void addToRecord(String filepath,String editTerm,String addedName){

    String animal= "";

    try{
        FileWriter fw=new FileWriter(filepath,true);
        BufferedWriter bw=new BufferedWriter(fw);
        PrintWriter pw=new PrintWriter(bw);
            if (animal.equals(editTerm)){
                pw.println(editTerm+","+addedName);
                pw.flush();
                pw.close();
            }
        System.out.println("Your Record was saved");
    }
    catch(Exception e){
        System.out.println("Your Record was not saved");
        e.printStackTrace();
    }
}

Answer 1

您可以使用此代码将文件内容“Fish”替换为“Fish, Ron”

public static void addToRecord(String filepath, String editTerm, String addedName) {

    try (Stream<String> input = Files.lines(Paths.get(filepath));
         PrintWriter output = new PrintWriter("Output.csv", "UTF-8"))
    {
        input.map(s -> s.replaceAll(editTerm, editTerm + "," + addedName))
                .forEachOrdered(output::println);

    } catch (IOException e) {
        e.printStackTrace();
    }
}

Answer 2

您可以考虑使用 CSV 库来帮助您解析 CSV，因为它比看起来更复杂，尤其是涉及到引用时。

这是一个使用 OpenCSV 的简单示例，它克隆原始 CSV 文件并根据需要添加“Ron”：

public class Csv1 {
    public static void main(String[] args) throws IOException, CsvValidationException {
        addToRecord("animal.csv", "animal-new.csv", "fish", "Ron");
    }

    public static void addToRecord(String filepathIn, String filepathOut, String editTerm, String addedName)
            throws IOException, CsvValidationException {

        try (CSVReader reader = new CSVReader(new FileReader(filepathIn))) {
            try (CSVWriter writer = new CSVWriter(new FileWriter(filepathOut))) {

                String[] values;
                while ((values = reader.readNext()) != null) {
                    if (values.length > 2 && values[0].equals(editTerm)) {
                        values[1] = addedName;
                    }
                    writer.writeNext(values);
                }
            }
        }
    }
}

给定文件：

type,name,age
fish,,10
cat,,12
lion,tony,10

将产生：

"type","name","age"
"fish","Ron","10"
"cat","","12"
"lion","tony","10"

（您可以在生成的 CSV 中查找有关输出引号的答案）

Answer 3

此处的要求是如果动物名称匹配，则添加一个额外的列。这相当于更改文件中的特定行。这是实现相同目的的简单方法，（不使用任何额外的库），

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;

public class EditLineInFile {

    public static void main(String[] args) {

        String animal = "Fish";

        Path path = Paths.get("C:\Zoo.csv");
        try {
            List<String> allLines = Files.readAllLines(path);
            int counter = 0;
            for (String line : allLines) {
                if (line.equals(animal)) {
                    line += ",Ron";
                    allLines.set(counter, line);
                }
                counter++;
            }
            Files.write(path, allLines);

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

将数据添加到 CSV 文件中的特定记录

Add data to specific record in CSV file

java

csv

file

record