读取字符串 IP 地址以存储在 2D 字符串数组中

Question

我有一个带有一组IP地址的文本文件，我用BufferedReader读取它，想将其存储在2D字符串数组中。

这是我的文本文件：

102.168.212.226, 104.170.214.228, 0 57.68.58.212, 59.70.60.214, 1 10.42.12.22, 12.44.14.24, 2 78.16.22.234, 80.18.24.236, 3 123.168.2.2, 125.170.4.4, 4

这是我的代码：

import java.io.;
import java.util.;
public class IPAddressLookup
    {
        IPAddressLookup()   //Constructor
        {
            int Width = 0, Height = 0;
            try
            {
                File fileA = new File("ClassA.txt");
                BufferedReader bra = new BufferedReader(new FileReader(fileA));
                String line = "";
                String[] str;
                while((line = bra.readLine()) != null )
                {
                    str = line.trim().split(", ");
                    Width = str.length;
                    Height++;
                }
                String [][] ClassATable = new String[Height][Width];
                for(int i = 0; i < Height; i++)
                {
                    if((line = bra.readLine()) != null )
                    {
                        str = line.trim().split(", ");
                        for(int j = 0; j < Width; j++)
                            ClassATable[i][j] = str[j];
                    }
                }
                for(int i = 0; i < Height; i++)
                    for(int j = 0; j < Width; j++)
                        System.out.println(ClassATable[i][j]);
                System.out.println("The text file contains:");
                System.out.println("Row : " +Height);
                System.out.println("Column : " +Width);
            }
            catch(IOException e)
            {
                System.out.println("Error: File not found.");
            }
        }
        public static void main(String args[])
        {
            IPAddressLookup acnl1 = new IPAddressLookup();
        }
    }

问题是当我尝试打印 String 数组时，它在输出中显示"null"。还有没有办法从文件中读取字符串 IP 地址并将它们存储在整数 2D 数组中？

我对Java有点陌生。谁能帮我解决这个问题？

Answer 1

您似乎正在读取文件两次，但您没有重置读取器，以便在第二个循环中，您从顶部重新开始。

您需要添加如下内容：在循环之间bra.getChannel().position(0)（在此之后：String [][] ClassATable = new String[Height][Width];）。这将重置您的阅读器，以便它可以从顶部再次启动。

Answer 2

试试这段代码：

public class IPAddressLookup {
ArrayList<String[]> ip = new ArrayList<>();
IPAddressLookup()   //Constructor
{
    int Width = 0, Height = 0;
    try
    {
        File fileA = new File("ClassA.txt");
        BufferedReader bra = new BufferedReader(new FileReader(fileA));
        String line = "";
        String[] str;
        while((line = bra.readLine()) != null )
        {
            str = line.trim().split(", ");
            ip.add(str);
            Width = str.length;
            Height++;
        }
        String [][] ClassATable = new String[Height][Width];
        for(int i=0 ; i<ip.size();i++){
            String[] temp = ip.get(i);
            for(int j=0;j<temp.length;j++){
                ClassATable[i][j] = temp[j];
            }
        }

        for(int i = 0; i < Height; i++)
            for(int j = 0; j < Width; j++)
                System.out.println(ClassATable[i][j]);
        System.out.println("The text file contains:");
        System.out.println("Row : " +Height);
        System.out.println("Column : " +Width);
    }
    catch(IOException e)
    {
        System.out.println("Error: File not found.");
    }
}
public static void main(String args[])
{
    IPAddressLookup acnl1 = new IPAddressLookup();
}

}

结果：

102.168.212.226 104.170.214.228 0 57.68.58.212 59.70.60.214 1 10.42.12.22 12.44.14.24 2 78.16.22.234 80.18.24.236 3 123.168.2.2 125.170.4.4 4 The text file contains: Row : 5 Column : 3