Java Programming Tutorial – 81 – Reading from Files

///Java Programming Tutorial – 81 – Reading from Files

Java Programming Tutorial – 81 – Reading from Files

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By |2020-08-16T08:54:42+00:00August 16th, 2020|Java Video Tutorials|24 Comments

24 Comments

  1. RajeeRim August 16, 2020 at 8:54 am - Reply

    Either remove while or remove multiple statements!

  2. Fahad Asad August 16, 2020 at 8:54 am - Reply

    Bucky made a file named chinese and was coughing in this tutorial. He tried to warn us all but we didn't listen.

  3. Mr. Marcial Glori August 16, 2020 at 8:54 am - Reply

    ūüėäthanks

  4. Fatima August 16, 2020 at 8:54 am - Reply

    i did the same like you but instead of showing me the text on console it says null in a continuous way. How can i resolve this issue? Please help

  5. Doctor Doom August 16, 2020 at 8:54 am - Reply

    Thank you man! You are Godsent! =)

  6. brian tan August 16, 2020 at 8:54 am - Reply

    if your code doesn't work when you used
    String a = x.next();

    String b = x.next();

    String c = x.next();
    it means that you have not given 3 kinds of data in one line or you have more. example 120 bucky roberts. a=120 b=bucky c=roberts.

  7. Randiir August 16, 2020 at 8:54 am - Reply

    For people having the file not found error, this is what worked for me:
    Put the file in the project folder (not the src one) and write it's name without the file type (.txt). Also you can use the files' exists method to check if the program can see it before giving it to the scanner:

    File f = new File("test.txt");

    System.out.println(f.exists());

    sc= new Scanner(f);

    This should print "true"

  8. John Nar August 16, 2020 at 8:54 am - Reply

    Hey I know this is probably a long shot considering how old the video is but if you could respond that would be awesome. I was wondering how you split up that string and give them variables. Thank you so much if you are seeing this.

  9. Imad Eddine terkmani August 16, 2020 at 8:54 am - Reply

    thank you, you save me

  10. OTTERBOTTER August 16, 2020 at 8:54 am - Reply

    Dude you totally saved me!! THANK YOU!!!!

  11. Jhin August 16, 2020 at 8:54 am - Reply

    you're the savior i never met

  12. Vlada Gherasim August 16, 2020 at 8:54 am - Reply

    THANK YOU <3

  13. Kumasi m√°ni August 16, 2020 at 8:54 am - Reply

    x = new Scanner (new File ("../name of main folder/src/name of file "));
    thank me later

  14. MilkTable August 16, 2020 at 8:54 am - Reply

    3:53 what if i have a custom public class 'Item' and instead of doing what's shown in the video, I wanna instantiate into 'Item' object? Hope this question makes sense

  15. Jovindio Wieuse August 16, 2020 at 8:54 am - Reply

    He's gone. I'm sad.

  16. Great t2 August 16, 2020 at 8:54 am - Reply

    We miss you! <3

  17. carl August 16, 2020 at 8:54 am - Reply

    youre always the best until now, this basics help alot thank you BUCKY… btw please comeback to YT

  18. Blackjac August 16, 2020 at 8:54 am - Reply

    amazing vid, cheers man

  19. Cj Meyer August 16, 2020 at 8:54 am - Reply

    I have to make a program that has 4 different text files and a main that exercises them, do I have to have a catch for all of them and can I use buffered reader for all of them?

  20. Daniel S August 16, 2020 at 8:54 am - Reply

    Can you use Print Writer in the same place? And stor it into that text file?

  21. SKY BLAZE August 16, 2020 at 8:54 am - Reply

    why is the chinese file cant be red by netbeans ūüėÖ

  22. Josue Sierra August 16, 2020 at 8:54 am - Reply

    are you creating new classes every time that you make a video?

  23. Emmanuel Obinna August 16, 2020 at 8:54 am - Reply

    Thank you very much for your tutorials…… i'm still in the beginners part but am hoping to improve with your Videos. and i wish to speack to you in person one day.

  24. Chan Begum August 16, 2020 at 8:54 am - Reply

    import java.io.File;  // Import the File class

    File myObj = new File("filename.txt"); // Specify the filename

    The File class has many useful methods for creating and getting information about files. For example:

    MethodTypeDescriptioncanRead()BooleanTests whether the file is readable or notcanWrite()BooleanTests whether the file is writable or notcreateNewFile()BooleanCreates an empty filedelete()BooleanDeletes a fileexists()BooleanTests whether the file existsgetName()StringReturns the name of the filegetAbsolutePath()StringReturns the absolute pathname of the filelength()LongReturns the size of the file in byteslist()String[]Returns an array of the files in the directorymkdir()BooleanCreates a directory

    If you don't know what a package is, read our Java Packages Tutorial.

    Create a File

    Use the¬†createNewFile()¬†method to create a file. This method returns a boolean value:¬†true¬†if the file was successfully created, and¬†false¬†if the file already exists. Note that the method is enclosed in a¬†try…catch¬†block. This is necessary because it throws an¬†IOException¬†if an error occurs (if the file cannot be created for some reason):

    Example

    import java.io.File;  // Import the File class
    import java.io.IOException;  // Import the IOException class to handle errors

    public class CreateFile {
      public static void main(String[] args) {
        try {
          File myObj = new File("filename.txt");
          if (myObj.createNewFile()) {
            System.out.println("File created: " + myObj.getName());
          } else {
            System.out.println("File already exists.");
          }
        } catch (IOException e) {
          System.out.println("An error occurred.");
          e.printStackTrace();
        }
      }
    }

    The output will be:

    File created: filename.txt

    Run example ¬Ľ

    To create a file in a specific directory (requires permission), specify the path of the file and use double backslashes to escape the "" character (for Windows). On Mac and Linux you can just write the path, like: /Users/name/filename.txt

    Example

    File myObj = new File("C:\Users\MyName\filename.txt");

    Run example ¬Ľ

    Get File Information

    Now that we have created a file, we can use other File methods to get information about that file:

    Example

    import java.io.File;

    public class GetFileInfo {
      public static void main(String[] args) {
        File myObj = new File("filename.txt");
        if (myObj.exists()) {
          System.out.println("File name: " + myObj.getName());
          System.out.println("Absolute path: " + myObj.getAbsolutePath());
          System.out.println("Writeable: " + myObj.canWrite());
          System.out.println("Readable " + myObj.canRead());
          System.out.println("File size in bytes " + myObj.length());
        } else {
          System.out.println("The file does not exist.");
        }
      }
    }

    The output will be:

    File name: filename.txt
    Absolute path: C:UsersMyNamefilename.txt
    Writeable: true
    Readable: true
    File size in bytes: 0

    Run example ¬Ľ

    Write To a File

    In the following example, we use the FileWriter class together with its write() method to write some text to the file we created in the example above. Note that when you are done writing to the file, you should close it with the close() method:

    Example

    import java.io.FileWriter;   // Import the FileWriter class
    import java.io.IOException;  // Import the IOException class to handle errors

    public class WriteToFile {
      public static void main(String[] args) {
        try {
          FileWriter myWriter = new FileWriter("filename.txt");
          myWriter.write("Files in Java might be tricky, but it is fun enough!");
          myWriter.close();
          System.out.println("Successfully wrote to the file.");
        } catch (IOException e) {
          System.out.println("An error occurred.");
          e.printStackTrace();
        }
      }
    }

    The output will be:

    Successfully wrote to the file.

    Run example ¬Ľ

    Read a File

    In the following example, we use the Scanner class to read the contents of the text file we created in the example above:

    Example

    import java.io.File;  // Import the File class
    import java.io.FileNotFoundException;  // Import this class to handle errors
    import java.util.Scanner; // Import the Scanner class to read text files

    public class ReadFile {
      public static void main(String[] args) {
        try {
          File myObj = new File("filename.txt");
          Scanner myReader = new Scanner(myObj);
          while (myReader.hasNextLine()) {
            String data = myReader.nextLine();
            System.out.println(data);
          }
          myReader.close();
        } catch (FileNotFoundException e) {
          System.out.println("An error occurred.");
          e.printStackTrace();
        }
      }
    }

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