BufferedReader跳过每一行

时间:2012-10-08 15:57:45

标签: java csv bufferedreader

从CSV中读取并跳过每隔一行。我有两个CSV文件,一个用于用户,一个用于属性 - 密钥ID是用户。

    String userName;
    static String breakLine = "\n--------------------\n";
        /**
        * Method to create a new user in a CSV File
        * @param sFileName
        * @param user
        */
   static void writeToCsvFile(String sFileName, User user)
   {
    try
    {
        FileWriter writer = new FileWriter(sFileName, true);


        writer.append(user.displayUserName()); // get username from userinput
        writer.append(","); // tabs to next record

        writer.append(user.getPassword()); //gets password from userinput
        writer.append(","); //tabs to next record
        writer.append("\n");

        writer.flush();
        writer.close();
        System.out.print("\nUser Successfully Created\n");
    }
    catch(IOException e)
    {
         e.printStackTrace();
    } 

   }





   /**
    * Class to read User information from specified CSV file
    * @param sFileName
    * @param user
    * @throws FileNotFoundException
    */
   static boolean readFromCsvFile(String sFileName, User user) throws FileNotFoundException
   {
       String thisLine;
       BufferedReader reader = new BufferedReader(new FileReader(sFileName));


        try
        {

        //  thisLine = reader.readLine();
          //System.out.print(thisLine);


           while((thisLine = reader.readLine()) != null)
                {
                    String userDetails[] = thisLine.split(",");

                    if ((user.displayUserName().equals(userDetails[0])))
                    {
                        System.out.print("\nUser <-" + user.displayUserName() + " -> exists! Logging In\n\n");
                        return true;
                    }

                    else if ((thisLine = reader.readLine()) == null)
                    {
                        System.out.print("\nNo User Details Matching Those Entered Exist. Please Register or Recheck Details.");
                        return false;
                    }
               }

        }
        catch(IOException e)
        {
            System.out.print("\nUser does not exist\n"); 
            e.printStackTrace();
            return false;
        } 


        finally{
            try
            {   reader.close();
            }catch (IOException e){}}
        return false;
            }


   static void writeToPropertyFile(String sFileName, Property property)
   {

    try
    {
        FileWriter writer = new FileWriter(sFileName, true);



        writer.append(property.getUser()); // get username from userinput
        writer.append(","); // tabs to next record

        writer.append(property.getAddress()); //gets address from userinput
        writer.append(","); //tabs to next record

        writer.append(property.getValue()); //gets property value from userinput
        writer.append(","); //tabs to next record

        writer.append(property.getLocation()); //gets property type from userinput
        writer.append(","); //tabs to next record

        writer.append(property.getResidenceStatus()); //gets residence status from userinput
        writer.append(","); //tabs to next record

        writer.append(property.getPaymentStatus()); //gets payment status from userinput
        writer.append(","); //tabs to next record

        writer.append(property.totalTax(property.privateResidence));
        writer.append(",");

        writer.append("\n");

        writer.flush();
        writer.close();
        System.out.print("\nProperty Successfully Saved to " + property.getUser() + "\n");
    }
    catch(IOException e)
    {
         e.printStackTrace();
    } 

   }

/**
 * Method to read and print all properties belonging to a user
 * @param sFileName
 * @param property
 * @param userName
 * @throws FileNotFoundException
 */
static void readFromPropertyFile(String sFileName, String userName) throws FileNotFoundException
{

       String thisLine;
       BufferedReader reader = new BufferedReader(new FileReader(sFileName));


        try
        {
            //thisLine = reader.readLine(); //skips first line in CSV


           while((thisLine = reader.readLine()) != null)
                {

                    String propertyDetails[] = thisLine.split(",");



                    if (propertyDetails[0].equals(userName))
                    {
                    System.out.print("\nUser: " + propertyDetails[0] + "\nAddress: " + propertyDetails[1] + "\nEst. Value: " + propertyDetails[2]
                            + "\nLocation Cat: " + propertyDetails[3] + "\nPrivate Residence: " + propertyDetails[4] + "\nTax Paid: " + propertyDetails[5] +  "\nTax Due: " + propertyDetails[6] + breakLine);

                    }

                    else if ((thisLine = reader.readLine()) == null)
                        System.out.print("\nNo Further Properties Found For This User\n");


               }

        }
        catch(IOException e)
        {
            System.out.print("\nProperties do not exist\n"); 
            e.printStackTrace();
        } 


        finally{
            try
            {   reader.close();
            }catch (IOException e){}}
            }


}

我正在与以下用户一起运行

Chris,password
Michelle,password
Zach,password
etc (on seperate lines, seperated by appending \n at the end of the input stage)

每个奇数编号都在工作并检测到用户已登录,每秒都在跳过。我读了,我认为我没有像这个链接那样运行跳过的.nextLine(),但我只是在星期五开始使用CSV和BufferedReader!

BufferedReader readLine skipping every second line

1 个答案:

答案 0 :(得分:4)

它跳过每一行,因为你在每次迭代中读取两行而只使用奇数行。

我建议改为使用

while ((thisLine = reader.readLine()) != null) { // only read once per loop.
    String propertyDetails[] = thisLine.split(",");
    if (propertyDetails[0].equals(userName)) {
        System.out.print("\nUser: " + propertyDetails[0] + "\nAddress: " + propertyDetails[1] + "\nEst. Value: " + propertyDetails[2]
                + "\nLocation Cat: " + propertyDetails[3] + "\nPrivate Residence: " + propertyDetails[4] + "\nTax Paid: " + propertyDetails[5] + "\nTax Due: " + propertyDetails[6] + breakLine);

    }
}
// out side the loop.
System.out.print("\nNo Further Properties Found For This User\n");