Question

我已经阅读了一个csv文件并将所有数据放入一个字符串类型数组并显示该数组。现在我想搜索该数组中的字符串，最后它返回在数组中找到该字符串的次数。我的代码在下面

package countscv;

import com.opencsv.CSVReader;
import java.io.FileNotFoundException;

import java.io.IOException;
import javax.swing.JOptionPane;
import java.io.FileReader;
import java.util.Arrays;

public class Countscv {
    /** @param args the command line arguments */
    public static void main(String[] args) throws FileNotFoundException, IOException {

        //Build reader instance
        //Read data.csv
        //Default seperator is comma
        //Default quote character is double quote
        //Start reading from line number 2 (line numbers start from zero)
        CSVReader reader = new CSVReader(new FileReader("res.csv"), ',' , '"' , 1);

        //Read CSV line by line and use the string array as you want
        String search="Brazil";
        int counter=0;
        String[] nextLine;
        while ((nextLine = reader.readNext()) != null) {
            if (nextLine != null) {
                //Verifying the read data here
                System.out.println(Arrays.toString(nextLine));
            }
        }
        for(int i=0;i<nextLine.length;i++)
        {
            if((nextLine[i].equals(search)))
            {
                counter++;
            }
        }
        System.out.print(counter);
    }
}

它显示带有nullpointer异常的数组。可能是错误？请帮助任何人。

Answer 1

for循环尝试使用nextLine，因为while循环已经到达它，所以此时为null。你需要计算while循环内部。请尝试以下方法：

CSVReader reader = new CSVReader(new FileReader("res.csv"), ',' , '"' , 1);
String search = "Brazil";
int counter = 0;
String[] nextLine;
while ((nextLine = reader.readNext()) != null) {
    for(String word : nextLine) {
        if (word.equals(search)) {
            counter++;
        }
    }
}
System.out.println(counter);

如何在字符串数组中搜索字符串并在java中返回其计数？

1 个答案: