Reading a txt file using Scanner class in Java

Question

I am working on a Java program that reads a text file line-by-line  each with a number  takes each number throws it into an array  then tries and use insertion sort to sort the array  I need help with getting the program to read the text file   I am getting the following error messages    java io FileNotFoundException  10 Random  The system cannot find the file specified  at java io FileInputStream open Native Method  at java io FileInputStream  lt init gt  Unknown Source  at java util Scanner  lt init gt  Unknown Source  at insertionSort main insertionSort java 14     I have a copy of the  txt file in my  src   bin  and main project folder but it still cannot find the file  I am using Eclipse by the way   import java io File  import java io FileNotFoundException  import java util Scanner   public class insertionSort    public static void main String   args         File file   new File  10 Random         try            Scanner sc   new Scanner file            while  sc hasNextLine                  int i   sc nextInt                System out println i                     sc close               catch  FileNotFoundException e            e printStackTrace

User · Answer

By the way it worth setting up the character encoding as well   Scanner scanner   new Scanner new File  C   tmp  edit1 txt     UTF-16

User · Answer

Make sure the filename is correct  proper capitalisation  matching extension etc - as already suggested   Use the Class getResource method to locate your file in the classpath - don t rely on the current directory   URL url   insertionSort class getResource  10 Random     File file   new File url toURI      Specify the absolute file path via command-line arguments   File file   new File args 0       In Eclipse    Choose  Run configurations  Go to the  Arguments  tab Put your  c  my file is here 10 Random txt or whatever  into the  Program arguments  section

User · Answer

You need the specify the exact filename  including the file extension  e g  10 Random txt  The file needs to be in the same directory as the executable if you want to refer to it without any kind of explicit path  While we re at it  you need to check for an int before reading an int  It is not safe to check with hasNextLine   and then expect an int with nextInt    You should use hasNextInt   to check that there actually is an int to grab  How strictly you choose to enforce the one integer per line rule is up to you  of course

User · Answer

Use following codes to read the file   import java io File  import java util Scanner   public class ReadFile        public static void main String   args             try               System out print  Enter the file name with extension                    Scanner input   new Scanner System in                File file   new File input nextLine                  input   new Scanner file                 while  input hasNextLine                      String line   input nextLine                    System out println line                             input close               catch  Exception ex                ex printStackTrace                         -  This application is printing the file content line by line

User · Answer

The file you read in must have exactly the file name you specify   10 random  not  10 random txt  not  10 random blah   it must exactly match what you are asking for  You can change either one to match so that they line up  but just be sure they do  It may help to show the file extensions in whatever OS you re using   Also  for file location  it must be located in the working directory  same level  as the final executable  the  class file  that is the result of compilation

User · Answer

You have to put file extension here  File file   new File  10 Random txt

User · Answer

here are some working and tested methods   using Scanner  package io   import java io File  import java util Scanner   public class ReadFromFileUsingScanner       public static void main String   args  throws Exception           File file new File  C   Users  pankaj  Desktop  test java            Scanner sc new Scanner file           while sc hasNextLine                 System out println sc nextLine                         Here s another way to read entire file  without loop  using Scanner class  package io   import java io File  import java io FileNotFoundException  import java util Scanner   public class ReadingEntireFileWithoutLoop       public static void main String   args  throws FileNotFoundException           File file new File  C   Users  pankaj  Desktop  test java            Scanner sc new Scanner file           sc useDelimiter    Z            System out println sc next               using BufferedReader   package io  import java io    public class ReadFromFile2       public static void main String   args throws Exception           File file new File  C   Users  pankaj  Desktop  test java            BufferedReader br new BufferedReader new FileReader file            String st          while  st br readLine     null               System out println st                       using FileReader  package io  import java io    public class ReadingFromFile       public static void main String   args  throws Exception           FileReader fr new FileReader  C   Users  pankaj  Desktop  test java            int i          while  i fr read     -1               System out print  char  i

User · Answer

You should use either   File file   new File  bin 10 Random txt      Or   File file   new File  src 10 Random txt      Relative to the project folder in Eclipse

User · Answer

No one seems to have addressed the fact that your not entering anything into an array at all  You are setting each int that is read to  i  and then outputting it   for  int i  0   sc HasNextLine   i          array i    sc NextInt        Something to this effect will keep setting values of the array to the next integer read   Than another for loop can display the numbers in the array   for  int x 0 x lt  array length   x          System out println  array x

User · Answer

File Path Seems to be an issue here please make sure that file exists in the correct directory or give the absolute path to make sure that you are pointing to a correct file  Please log the file getAbsolutePath   to verify that file is correct

User · Answer

private void loadData          Scanner scanner   null      try           scanner   new Scanner new File getFileName              while  scanner hasNextLine                  Scanner lijnScanner   new Scanner scanner nextLine                  lijnScanner useDelimiter                   String stadVan   lijnScanner next                String stadNaar   lijnScanner next                double km   Double parseDouble lijnScanner next                  this voegToe new TweeSteden stadVan  stadNaar   km                    catch  FileNotFoundException e            throw new DbException e getMessage    e         finally           if scanner    null               scanner close

User · Answer

At first check the file address  it must be beside your  java file or in any address that you define in classpath environment variable  When you check this then try below    you must use a file name by it s extension in File object constructor  as an example   File myFile   new File  test txt    but there is a better way to use it inside Scanner object by pass the filename absolute address  as an example   Scanner sc   new Scanner Paths get  test txt       in this way you must import java nio file Paths as well

[java] Reading a .txt file using Scanner class in Java

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