在Java中，从文件中读取一组数字，例如1到3，4到16

在循环中，我想从一个有n行的csv文件中读取数字。在循环的每一次迭代中，我想从上一组结束的下一组数字开始。例如，我的文件有编号1、2、3、4…….N

比方说，我想在每次迭代中读取3个数字，或者在每次迭代中读取用户定义的任何值。 迭代1：编号1、2、3 迭代2：编号4、5、6

下面是我尝试过的示例代码

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();

    }
}

}

我希望输出如下所示：

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

我的文件看起来像

---

非常感谢您的帮助。

打印后将

testString

设置为

”

（空字符串）（

testString=“”；

）

完整代码：

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();
    }
}

---

你几乎做到了，你只需要重新启动字符串

    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();

System.out.println（“文件读取测试”）；
BufferedReader BufferedReader=new BufferedReader（new FileReader（“/Users/cesarjesusgutierrez/Downloads/test.csv”）；
String line=bufferedReader.readLine（）；
字符串testString=“”；
int rowCount=3//基于此变量，在每次迭代中拾取的项目数
int-itr=1；
int l=1；
对于（int z=1；z我认为如果您使用调试器运行代码，您可以自己发现问题。您使用的IDE应该有一个。您应该学会使用它。您读过这个吗？查看您正在读取的文件会有帮助。谢谢。这很有帮助。如果我想要类似于此测试开始的输出，我还有一个问题字符串是[{1}，{2}，{3}]测试字符串的结束测试字符串的开始是[{4}{5}{6}]测试字符串的结束测试字符串的开始是[{7}{8}{9}]测试字符串的结束测试字符串的开始是[{10}{11}{12}]测试字符串的结尾谢谢。这很有帮助。我还有一个问题，如果我想要像这样的输出，测试字符串的开头是[{1}，{2}，{3}]测试字符串的结尾是[{4}{5}{6}]测试字符串的结尾测试字符串的开头是[{7}{8}{9}]测试字符串的结尾测试字符串的开头是[{10}{11}{12}]测试字符串的结尾测试字符串是{13}{14}{15}这将是一个新问题。嘿，塞萨尔，我已经更新了我的问题，你有什么建议吗
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();
    }
}

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}

    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();