Reading and displaying data from a .txt file

Question

How do you read and display data from .txt files?

Answer 1

BufferedReader in = new BufferedReader(new FileReader("<Filename>"));

Then, you can use in.readLine(); to read a single line at a time. To read until the end, write a while loop as such:

String line;
while((line = in.readLine()) != null)
{
    System.out.println(line);
}
in.close();

Answer 2

If your file is strictly text, I prefer to use the java.util.Scanner class.

You can create a Scanner out of a file by:

Scanner fileIn = new Scanner(new File(thePathToYourFile));

Then, you can read text from the file using the methods:

fileIn.nextLine(); // Reads one line from the file
fileIn.next(); // Reads one word from the file

And, you can check if there is any more text left with:

fileIn.hasNext(); // Returns true if there is another word in the file
fileIn.hasNextLine(); // Returns true if there is another line to read from the file

Once you have read the text, and saved it into a String, you can print the string to the command line with:

System.out.print(aString);
System.out.println(aString);

The posted link contains the full specification for the Scanner class. It will be helpful to assist you with what ever else you may want to do.

Answer 3

In general:

• Create a FileInputStream for the file.
• Create an InputStreamReader wrapping the input stream, specifying the correct encoding
• Optionally create a BufferedReader around the InputStreamReader, which makes it simpler to read a line at a time.
• Read until there's no more data (e.g. readLine returns null)
• Display data as you go or buffer it up for later.

If you need more help than that, please be more specific in your question.

Answer 4

I love this piece of code, use it to load a file into one String:

File file = new File("/my/location");
String contents = new Scanner(file).useDelimiter("\\Z").next();

Answer 5

Below is the code that you may try to read a file and display in java using scanner class. Code will read the file name from user and print the data(Notepad VIM files).

import java.io.*;
import java.util.Scanner;
import java.io.*;

public class TestRead
{
public static void main(String[] input)
{
    String fname;
    Scanner scan = new Scanner(System.in);

    /* enter filename with extension to open and read its content */

    System.out.print("Enter File Name to Open (with extension like file.txt) : ");
    fname = scan.nextLine();

    /* this will reference only one line at a time */

    String line = null;
    try
    {
        /* FileReader reads text files in the default encoding */
        FileReader fileReader = new FileReader(fname);

        /* always wrap the FileReader in BufferedReader */
        BufferedReader bufferedReader = new BufferedReader(fileReader);

        while((line = bufferedReader.readLine()) != null)
        {
            System.out.println(line);
        }

        /* always close the file after use */
        bufferedReader.close();
    }
    catch(IOException ex)
    {
        System.out.println("Error reading file named '" + fname + "'");
    }
}

}

Answer 6

public class PassdataintoFile {

    public static void main(String[] args) throws IOException  {
        try {
            PrintWriter pw = new PrintWriter("C:/new/hello.txt", "UTF-8");
            PrintWriter pw1 = new PrintWriter("C:/new/hello.txt");
             pw1.println("Hi chinni");
             pw1.print("your succesfully entered text into file");
             pw1.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        BufferedReader br = new BufferedReader(new FileReader("C:/new/hello.txt"));
           String line;
           while((line = br.readLine())!= null)
           {
               System.out.println(line);
           }
           br.close();
    }

}

Answer 7

In Java 8, you can read a whole file, simply with:

public String read(String file) throws IOException {
  return new String(Files.readAllBytes(Paths.get(file)));
}

or if its a Resource:

public String read(String file) throws IOException {
  URL url = Resources.getResource(file);
  return Resources.toString(url, Charsets.UTF_8);
}

Answer 8

If you want to take some shortcuts you can use Apache Commons IO:

import org.apache.commons.io.FileUtils;

String data = FileUtils.readFileToString(new File("..."), "UTF-8");
System.out.println(data);

:-)

Answer 9

You most likely will want to use the FileInputStream class:

int character;
StringBuffer buffer = new StringBuffer("");
FileInputStream inputStream = new FileInputStream(new File("/home/jessy/file.txt"));

while( (character = inputStream.read()) != -1)
        buffer.append((char) character);

inputStream.close();
System.out.println(buffer);

You will also want to catch some of the exceptions thrown by the read() method and FileInputStream constructor, but those are implementation details specific to your project.