如何从 csv 文件中读取特定范围并写入 Java 中的另一个 csv 文件？

Question

This is the code I have been using to read all the records from CSV file. I am quite new to the java.

FileReader openFile = new FileReader("/Users/ABC/Desktop/Test/myFirstFile.csv"); 

    BufferedReader readMyDataObj = new BufferedReader(openFile)
    FileWriter writer2 = new FileWriter("/Users/ABC/Desktop/Test/mySecondFile.csv");
    BufferedWriter bf2 = new BufferedWriter(writer2);
    String data2;
    while ((data2=readMyDataObj.readLine())!=null) {    
    bf2.write(data2);
    bf2.newLine();       
     }
    bf2.close();                   
    writer2.close();
    openFile.close();

Answer 1

here is a very good example for your requirement - read and also filter examples are present https://mkyong.com/java8/java-8-stream-read-a-file-line-by-line/

Answer 2

If you want to write data to a JSON file your best bet is to use a standard Java library like org.json !

Answer 3

You can achieve your desired results by using some variables and a counter around the main while loop. Also, it might make sense to take into account whether or not the input csv file has a header row.

Main.java

    public static void main(String[] args) throws IOException {
        FileReader inFile = new FileReader("a.csv");
        BufferedReader inReader = new BufferedReader(inFile);

        FileWriter outFile = new FileWriter("b.csv");
        BufferedWriter outWriter = new BufferedWriter(outFile);

        // Range to read/write
        int low = 5;
        int high = 10;

        int count = 1;
        String line = inReader.readLine();
        while (line != null && count < high) {
            if (count >= low) {
                outWriter.write(line);
                outWriter.newLine();
            }

            line = inReader.readLine();
            count++;
        }

        inReader.close();
        inFile.close();
        outWriter.close();
        outFile.close();
    }

a.csv

ID,First Name,Last Name,City,State,Age,Height
iW00K,Jane,Bosco,Lake Dandreland,ME,61,170.57
BzxTl,Steve,Smith,Uniqueside,PA,35,152.93
vobj8,Tony,Auer,Tressiestad,MS,63,160.86
X78RS,Steve,Cole,Port Zellachester,OH,72,159.84
0YpWG,John,Lu,East Vernaview,OH,18,200
4JaoZ,Peter,Simonis,Wernerchester,HI,25,161.64
hP48C,Tom,Lu,Uniqueside,ME,45,161.64
WDQpb,John,Casper,East Felicityshire,OH,42,170.57
wyPwB,Jane,Johns,Maggiehaven,CA,16,180.42
VCtYR,Peter,Jast,Schadenberg,ME,41,161.64
1VYOs,John,Daniel,Port Zellachester,HI,34,200
V7pg9,Tom,Mayert,Schadenberg,OH,71,152.93
SmE9w,Jane,Lu,Stephanchester,HI,25,176.95
ALyok,Tom,Smith,Ryanchester,PA,70,176.95
fgE5v,Peter,Bailey,Bednarstad,PA,67,170.24
eBIIM,Peter,Haley,East Vernaview,MS,65,161.64
5sv4L,Peter,Prosacco,Uniqueside,PA,50,178.25
a48IS,Peter,Marvin,Kossview,OH,63,200
9mLcZ,John,VonRueden,East Vernaview,PA,20,174.24

b.csv

X78RS,Steve,Cole,Port Zellachester,OH,72,159.84
0YpWG,John,Lu,East Vernaview,OH,18,200
4JaoZ,Peter,Simonis,Wernerchester,HI,25,161.64
hP48C,Tom,Lu,Uniqueside,ME,45,161.64
WDQpb,John,Casper,East Felicityshire,OH,41,170.57