從 Java 中的文件中讀取一組數字，設置為 1 到 3、4 到 16

Question

在一個循環中，我想從具有 n 行數的 csv 文件中讀取數字。 在循環的每次迭代中，我想從上一組結束的下一組數字開始。 例如，我的文件有數字 1、2、3、4........N

可以說，我想在每次迭代中讀取 3 個數字或用戶定義在每次迭代中讀取的任何值。 迭代 1：編號 1、2、3 迭代 2：編號 4、5、6

這是我嘗試過的示例代碼

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

public class FileReadTest {

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

        for (int z = 1; z <= 5; z++) {
            System.out.println("File Read Test Iteration "+z);
            BufferedReader bufferedReader = new BufferedReader(new FileReader("testNumbers.csv"));
            String line = bufferedReader.readLine();
            String testString = "Start of the string";

            int rowCount = 3; //5
            int itr = 1;
            int l = 1;
            while (line != null && itr <= (l * rowCount)) {
                itr++;
                testString += "{" + line.split(",")[0] + "}";
                line = bufferedReader.readLine();
                if (itr < (l * rowCount + 1)) testString += ",";
            }
            l++;
        testString += "end of the string";
        System.out.println(testString);
        bufferedReader.close();

    }
}

}

目前我正在退出：

File Read Test Iteration 1
Start of the string{1},{2},{3}end of the string
File Read Test Iteration 2
Start of the string{1},{2},{3}end of the string
File Read Test Iteration 3
Start of the string{1},{2},{3}end of the string
File Read Test Iteration 4
Start of the string{1},{2},{3}end of the string
File Read Test Iteration 5
Start of the string{1},{2},{3}end of the string

我希望 output 類似於：

File Read Test Iteration 1
Start of the string{1},{2},{3}end of the string
File Read Test Iteration 2
Start of the string{4},{5},{6}end of the string
File Read Test Iteration 3
Start of the string{7},{8},{9}end of the string
File Read Test Iteration 4
Start of the string{10},{11},{12}end of the string
File Read Test Iteration 5
Start of the string{13},{14},{15}end of the string

我的文件看起來像在此處輸入圖像描述

任何幫助是極大的贊賞。

Answer 1

打印后將testString設置為"" （空字符串）（ testString = ""; ）。

System.out.println("test string is " + testString);
testString = "";
l++;

完整代碼：

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

public class FileReadTest {

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


        System.out.println("File Read Test");
        BufferedReader bufferedReader = new BufferedReader(new FileReader("testNumbers.csv"));
        String line = bufferedReader.readLine();
        String testString = "";

        int rowCount = 3; //Based on this variable, the number of items to picked in each iteration
        int itr = 1;
        int l = 1;

        for (int z = 1; z <= 5; z++) {

            while (line != null && itr <= (l * rowCount)) {
                itr++;
                testString += "{" + line.split(",")[0] + "}";
                line = bufferedReader.readLine();
            }
            System.out.println("test string is " + testString);
            testString = "";
            l++;
        }
        bufferedReader.close();
    }
}

Output：

File Read Test
test string is {1}{2}{3}
test string is {4}{5}{6}
test string is {7}{8}{9}
test string is {10}{11}{12}
test string is {13}{14}{15}

Answer 2

你幾乎做到了，你只需要重新啟動字符串

    System.out.println("File Read Test");
    BufferedReader bufferedReader = new BufferedReader(new FileReader("/Users/cesarjesusgutierrez/Downloads/test.csv"));
    String line = bufferedReader.readLine();
    String testString = ""; 

    int rowCount = 3; //Based on this variable, the number of items to picked in each iteration
    int itr = 1;
    int l = 1;

    for (int z = 1; z <= 5; z++) {

        testString = ""; // check this :)
        while (line != null && itr <= (l * rowCount)) {
            itr++;
            testString += "{" + line.split(",")[0] + "}";
            line = bufferedReader.readLine();
        }
        System.out.println("test string is " + testString);
        l++;
    }
    bufferedReader.close();