java - Checking of a line is in a file with bufferedread and hashset -

my problem have write code check if customers name in txt file (customers.txt).

the problem check hashset if customer in file , says isn't in file while is.(checked manually) please me solve this.

the code have below.

    public class customer {     //declaration     public static string s;     private string line ;     public string namecustomer;   /**  * constructor  */ public klant(){}  /**checking of customer in file  */ public void getcustomer() {     // make simpleinoutdialog               simpleinoutdialog  input = new simpleinoutdialog("customers");         namecustomer = input.readstring("give in name");     try{     bufferedreader br = new bufferedreader(new filereader("l:\\documents/informatica/6de jaar/gip/customers.txt"));     hashset<string> hs = new hashset<string>();     int = 0;     while ((line = br.readline()) != null)     {         i++;         if (i == 1){hs.add(br.readline());}          if (i % 4 == 0){hs.add(br.readline());}      }     if(hs.contains(namecustomer)){         //the customer exists      input.showstring("the customer exists", "");      }else{input.showstring("the customer not exist, make new one", "");          setnieuweklant();}       }catch (exception e){//catch when there errors         system.err.println("error: " + e.getmessage());}  }   /**  * make new customer  */  public void make new customer(){     // make simpleinoutdialog          simpleinoutdialog  input = new simpleinoutdialog("a new customer");     //input     s = "name customer: " + input.readstring("give in name:"); writetofile(); s = "adress: " + input.readstring("give adress"); writetofile(); s = "telephonenummber: " + input.readstring("give telephonenumber"); writetofile(); //making customerid   uuid idcustomer = uuid.randomuuid();   s = "customerid: " + customerid.tostring(); writetofile();  }   /**  * schrijft de gegevens weg naar het bestand  */    public void writetofile(){ try{  filewriter writer = new filewriter("l:\\documents/informatica/6de jaar/gip/customer.txt", true); bufferedwriter out = new bufferedwriter(writer); //wrting away data out.write(s);  //closing writer out.close();   }catch (exception e){//catch when there errors     system.err.println("error: " + e.getmessage());     }     } 

dutcht code

public class klant {     //declaratie van de variabele die de tekst voorsteld     public static string s;     private string line ;     public string naamklant;   /**  * constructor  */ public klant(){}  /**controleerd of de klant al bestaat  */ public void getklant() {     // simpleinoutdialog aanmaken              simpleinoutdialog  input = new simpleinoutdialog("klanten");         naamklant = input.readstring("geef de volledige naam in");     try{     bufferedreader br = new bufferedreader(new filereader("l:\\documents/informatica/6de jaar/gip/klanten.txt"));     hashset<string> hs = new hashset<string>();     int = 0;     while ((line = br.readline()) != null)     {         i++;         if (i == 1){hs.add(br.readline());}          if (i % 4 == 0){hs.add(br.readline());}      }     if(hs.contains(naamklant)){         //klant bestaat      input.showstring("de klant bestaat", "");      }else{input.showstring("de klant bestaat niet, er wordt een nieuwe klant aangemaakt", "");          setnieuweklant();}       }catch (exception e){//catch wanneer er errors zijn         system.err.println("error: " + e.getmessage());}  }   /**  * maakt een nieuwe klant aan   */  public void setnieuweklant(){     // simpleinoutdialog aanmaken          simpleinoutdialog  input = new simpleinoutdialog("een nieuwe klant");     //input     s = input.readstring("geef de volledige naam in");     writetofile();     s = "adres: " + input.readstring("geef het adres op");     writetofile();     s = "telefoonummer: " + input.readstring("geef het telefoonnummer op");     writetofile();     //een klantennummer aanmaken        uuid idklant = uuid.randomuuid();       s = "klantnummer: " + idklant.tostring();     writetofile();  }   /**  * schrijft de gegevens weg naar het bestand  */ public void writetofile(){      try{          filewriter writer = new filewriter("l:\\documents/informatica/6de jaar/gip/klanten.txt", true);         bufferedwriter out = new bufferedwriter(writer);         //uw gegevens wegschrijven         out.write(s);         out.newline();         //de writer sluiten         out.close();       }catch (exception e){//catch wanneer er errors zijn         system.err.println("error: " + e.getmessage());}        }   } 

i'm not sure you're trying overall (reading every 4th line, etc.), wouldn't use hashset if want check if string exists in file.

here's complete program checking if string exists in file:

import java.io.*;  public class checkname {   private static boolean doesnameexistinfile(string name, string filename)     throws filenotfoundexception, ioexception   {     bufferedreader reader = new bufferedreader(new filereader(filename));      string line = null;      try {       while ((line = reader.readline()) != null) {         if (line.equals(name))           return true;       }      } {       // close() before exiting.       reader.close();     }      return false;   }    public static void main(string[] args)     throws filenotfoundexception, ioexception   {     boolean exists = doesnameexistinfile("bender", "input.txt");      system.out.println(exists ? "exists!" : "does not exist.");   } } 

contents of input file input.txt:

leela fry professor hermes zoidberg 

a couple of things note:

1. we don't read entire file. stop reading once we've found string, that's we're interested in.
2. always close() before exiting, whether string found or not. put call in finally block.