Question

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.StringTokenizer;


public class csvimport5 {


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


        double [][] data = new double [87][2];  
        File file = new File("buydata.txt");
        int row = 0;
        int col = 0;
        BufferedReader bufRdr  = new BufferedReader(new FileReader(file));
        String line = null;


        //read each line of text file
        while((line = bufRdr.readLine()) != null && row < data.length)
        {   
        StringTokenizer st = new StringTokenizer(line,",");
        while (st.hasMoreTokens())
        {
            //get next token and store it in the array
            data[row][col] = Double.parseDouble(st.nextToken());
            col++;
        }
        col = 0;
        row++;
        }

        System.out.println(" "+data[87][2]);      

      }

    }

错误讯息：

ArrayIndexOutOfBounds Exception at "System.out.println(" "+data[87][2]);

我的txt文件是：

8.00,28.00  
18.00,28.00 
8.00,23.00  
12.00,20.00 
15.00,30.00 
12.00,32.00 
12.00,20.00 
18.00,31.00 
29.00,25.00 
6.00,28.00  
7.00,28.00  
6.00,24.00
14.00,30.00 
11.00,23.00 
12.00,20.00 
31.00,24.00 
11.00,20.00 
17.00,23.00 
14.00,32.00 
15.00,23.00 
8.00,20.00  
17.00,31.00 
7.00,20.00
12.00,23.00 
15.00,20.00 
12.00,20.00 
21.00,20.00 
27.00,27.00 
18.00,20.00 
25.00,27.00 
46.00,13.00
26.00,10.00 
47.00,22.00 
44.00,14.00
34.00,4.00
34.00,4.00  
44.00,7.00  
39.00,5.00  
20.00,0.00  
43.00,11.00 
43.00,25.00 
34.00,2.00  
25.00,10.00 
50.00,9.00  
25.00,9.00  
39.00,2.00  
34.00,7.00  
44.00,15.00 
36.00,3.00  
40.00,5.00  
49.00,21.00 
42.00,7.00  
35.00,1.00  
30.00,2.00  
31.00,13.00 
53.00,12.00 
40.00,4.00  
26.00,4.00  
50.00,55.00
57.00,51.00 
62.00,52.00 
56.00,52.00 
59.00,40.00 
61.00,68.00 
66.00,49.00 
57.00,49.00
62.00,58.00 
47.00,58.00 
53.00,40.00 
60.00,54.00 
55.00,48.00 
56.00,65.00 
67.00,56.00 
55.00,43.00 
52.00,49.00 
67.00,62.00
68.00,61.00 
65.00,58.00 
46.00,53.00 
46.00,49.00 
47.00,40.00 
64.00,22.00 
64.00,54.00 
63.00,64.00 
63.00,56.00 
64.00,44.00 
63.00,40.00

Answer 1

data[87][2]确实是一个OutOfBound指数。

如果您使用[87][2]对数组进行实例化，则最后一个索引为data[86][1]，因为您的索引范围为[0...86]和[0...1]

Answer 2

double [][] data = new double [87][2];将创建一个大小为87和2的double [] []。

引用这些条目的索引是86和1（数组总是以索引“0”开头，而不是“1”）

尝试：

 System.out.println(" "+data[86][1]);

这应该有用！

Answer 3

Java中的任何数组对象的索引都是“n-1”。因此，数组的边界是0和86，其中data [0] [0]为您提供第一个元素，data [86] [1]为您提供最后一个元素。

替换：

System.out.println(" "+data[87][2]);

使用：

System.out.println(" "+data[86][1]);

Answer 4

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.io.FileUtils;

public class CSVReader {

    public static void main(String[] args) throws IOException {
        List<String[]> dataList = new ArrayList();
        File file = new File("/tmp/data.txt");
        List<String> lines = FileUtils.readLines(file, "UTF-8");
        for (String line : lines) {
            dataList.add(line.split(","));
        }
        String[] val = dataList.get(dataList.size() - 1);
        System.out.println("" + val[0] + " " + val[1]);
    }
}

正如其他人所说，你只是错了你的索引。除此之外，上面的代码是更清晰的做事方式，可能稍微节省一点......注意使用apache commons和内置字符串api。在方便的地方添加字符串以进行双重转换。

如何在Java中从.text文件中打印2D数组

4 个答案: