Question

我已将一组值从csv文件导入到数组列表中。现在我需要从每个元素中删除扩展名.tar，或者在从csv文件导入时只允许前8个字符插入到数组列表中。这是我的代码，我想在array1部分

中进行更改

import java.io.*;
import java.util.*;
import java.util.ArrayList;
import java.lang.*;


public class compare 
{
 public static void main(String[] args) 
 {
  ArrayList<String> array = new ArrayList<String>(); //Array for storing values
  ArrayList<String> array1 = new ArrayList<String>(); //Array for storing values

  try
  {
    String strFile = "D:\\Ramakanth\\PT2573\\ftp.csv"; //csv file containing data
    BufferedReader br = new BufferedReader( new FileReader(strFile)); //create BufferedReader to 
    String strLine = "";
    StringTokenizer st = null;

    while( (strLine = br.readLine()) != null) //read comma separated file line by line
    {
     st = new StringTokenizer(strLine, ","); //break comma separated line using ","

     while(st.hasMoreTokens())
     {
      array.add(st.nextToken()); //store csv values in array
     }
    }
   }
   catch(Exception e)
   {
    System.out.println("Exception while reading csv file: " + e);                  
   }

   try
   {
    String strFile1 = "D:\\Ramakanth\\PT2573\\target.csv";  //csv file containing data
    BufferedReader br1 = new BufferedReader( new FileReader(strFile1)); //create BufferedReader 
    String strLine1 = "";
    StringTokenizer st1 = null;

    while( (strLine1 = br1.readLine()) != null) //read comma separated file line by line
    {
     st1 = new StringTokenizer(strLine1, ","); //break comma separated line using ","

     while(st1.hasMoreTokens())
     {
      array1.add(st1.nextToken()); //store csv values in array
     }
    }
   }
   catch(Exception e)
   {
    System.out.println("Exception while reading csv file: " + e);                  
   }

   array.removeAll(array1);
   System.out.println(array);

   try
   {
   BufferedWriter br2 = new BufferedWriter(new FileWriter("D:\\Ramakanth\\PT2573\\output.csv"));
   StringBuilder sb1 = new StringBuilder();
   for (String element : array)
   {
    sb1.append(element);
    sb1.append(" ");
   }

   br2.write(sb1.toString());
   br2.close();
   }
   catch(Exception e)
   {
    System.out.println("Exception while writing csv file: " + e);                  
   }

  }
}

Answer 1

您可以使用

使用StringUtils.substringBefore课程

StringUtils.substringBefore(yourstring, ".tar" );

它会为您提供所需的输出

Answer 2

试试这个，

    String element = "extension.tar";

    int index = element.lastIndexOf(".");
    System.out.println("if Dot extension means : " + element.substring(0, index));
    element = element.substring(0, 8);

    System.out.println("if first 8 character means : " + element);

<强>输出：

如果Dot扩展意味着：扩展名

如果前8个字符表示：extensio

如何修剪java中arraylist中每个元素的最后4个字符？

2 个答案: