In this article, we will show you how to use java.io.BufferedReader to read content from a file
Note
Read this different ways read a file
Read this different ways read a file
1. Files.newBufferedReader (Java 8)
In Java 8, there is a new method Files.newBufferedReader(Paths.get("file")) to return a BufferedReader
filename.txt
A
B
C
D
E
FileExample1.java
package com.mkyong;
import java.io.BufferedReader;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
public class FileExample1 {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder();
try (BufferedReader br = Files.newBufferedReader(Paths.get("filename.txt"))) {
// read line by line
String line;
while ((line = br.readLine()) != null) {
sb.append(line).append("\n");
}
} catch (IOException e) {
System.err.format("IOException: %s%n", e);
}
System.out.println(sb);
}
}
Output
A
B
C
D
E
2. BufferedReader
2.1 A classic BufferedReader with JDK 1.7 try-with-resources to auto close the resources.
FileExample2.java
package com.mkyong;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class FileExample2 {
public static void main(String[] args) {
try (FileReader reader = new FileReader("filename.txt");
BufferedReader br = new BufferedReader(reader)) {
// read line by line
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
System.err.format("IOException: %s%n", e);
}
}
}
2.2 In the old days, we have to close everything manually.
FileExample3.java
package com.mkyong.calculator;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class FileExample3 {
public static void main(String[] args) {
BufferedReader br = null;
FileReader fr = null;
try {
fr = new FileReader("filename.txt");
br = new BufferedReader(fr);
// read line by line
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
System.err.format("IOException: %s%n", e);
} finally {
try {
if (br != null)
br.close();
if (fr != null)
fr.close();
} catch (IOException ex) {
System.err.format("IOException: %s%n", ex);
}
}
}
}
References
mkyong
Founder of Mkyong.com, passionate Java and open-source technologies. If you enjoy my tutorials, consider making a donation to these charities.
Very good and “to the point” article! Congrats!
Hey @mkyong, Thanks for all the wonderful work you are doing. A request if I may, would you be able to write some code to sort a csv on two columns(including datetime columns) please? I have written one and it works, but not very efficient. Thanks
@mkyong could you assist??
I am using bufferReader to read a 1gb file.
I do not want to keep entire file in memory until it get processed instead.
I want to keep data in memory as equal to my custom buffer size =let’s say 5*103kb where 103kb is the one line size.
When I use bufferReader.lines().count() ..I assume that it should return no’s of line=5 as my buffer size is 5*103 and each line has 103kb of text data.
But it returns the count of entire files lines I.e (1gb*1024*1024/103).
That what is use of buffer?? BufferReader.lines() do not respect the bufferSize????
Could you please help and elaborate??
Thanks,
Rk
Thank for share buddy
java how to learn.. anyone tell me.. best online website
Thanks
I doubt that the statement “try (BufferedReader br = new BufferedReader(new FileReader(FILENAME)))” will not close both BufferedReader and FileReader. To close both the readers, we need to use “try(FileReader fr = new FileReader(FILENAME); BufferedReader br = new BufferedReader(fr))”. Please check.
Thanks, article is updated.
try (FileReader reader = new FileReader("filename.txt");BufferedReader br = new BufferedReader(reader))
Excelent!
just for comment, in your first example, the line
“br = new BufferedReader(new FileReader(FILENAME));”
wasn’t necessary!
Thank you!
I learn a lot with you!
Article is updated, thanks for your comment.
Thank you this is anice example.
Thanks a bunch! You just saved my day.
Congratulations, for your posts, is has helped me a lot!
Hello sir pls send me code of BufferReader…Sir please…
HE HE HE HI
thanks you !
how to open multiple file in different directory
public Ceg(String file) {
Scanner scanner = null;
try {
scanner = new Scanner(new File(file));
} catch (FileNotFoundException ex) {
System.out.println(“Allomany megnyitasi hiba!!”);
System.exit(1);
}
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if (line.length() != 0) {
System.out.println(“***Line: ” + line);
StringTokenizer stk = new StringTokenizer(line, “, .;:?!”);
int id = Integer.parseInt(stk.nextToken());
String vezeteknev = stk.nextToken();
String keresztnev = stk.nextToken();
int eletkor = Integer.parseInt(stk.nextToken());
String beosztas = stk.nextToken();
Alkalmazott a = new Alkalmazott(id, vezeteknev, keresztnev, eletkor, beosztas);
this.alkalmazott.add(a);
}
}
}
it says the file is not found. what is wrong?
Create the file manually.
I created the file. I have used “thing.txt” and I have used “C:UsersJohnWorkspaceLunaSR2ReadFilething.txt”
I created thing.txt using Eclipse
Very Good article. Is there a way to access folder using authenitcation. Right now I’m using smb api for this. But it would be easier if the authentication can be done in this program.
Great and to the point, but I’m stuck on a ‘file not found’ exception because I put my file inside the src folder like this: src/res_folder/file.txt Does anyone know how to access that? I tried things like getResourceAsStream, get Resource, classloader, and putting the path as “/res_folder/file.txt” and other things but still have the same error.
ok, after hours and hours of looking I somehow accidentally figured it out myself, so I’ll just share it here for anyone else.
At this line: br = new BufferedReader(new FileReader(“C:\testing.txt”));
I changed it to: br = new BufferedReader(new FileReader(new File(“src/res/myfile.txt”)));
This works for me, but since I do more Android programming, I’m not sure if this is the best approach.
Verryyyyyyyyyyyyyy Guuuddddd!!!
What if when I want to read in file not from newline to newline but from some other token to token? Like from LABEL to LABEL etc. What tool should I use then?
i guess u have to use Scanner to read the file.
public class readFile
{
public static void main(String args[])
{
File f = new File(filePath);
Scanner read = new Scanner(f).useDelimeter(“put anything as a delimeter eg: ##”);
String content =read.next();
while((content=read.next()).hasNext())
{
content += content;
}
}
}
Itis a very good code. I alos have written some tips in Java for file access and manipulation including reading, writing, creating file, and folder,…http://www.worldbestlearningcenter.com/tips/Java-write-file.htm
Hi, your codes works fine but i am getting an encrypted version, so how can i get non-encrypted version.
How can you adapt the code to allow the variable “sCurrentline”, to be manipulated through methods such as, .split(), out side of the try-catch statement. It will not even print “sCurrentLine”, unless it is in side the try-catch statement.
Hi, where the txt file should be placed??
I created a txt file on the same folder of the java files and the application always throw the FileNotFoundException. I tried different names, different format files, but it never finds the file.
Thanks
you can save it anywhere but you have to save it with .java extension
The entire Java File Operation like Reading, writing, Delete are found here,
http://antguider.blogspot.in/2012/06/java-file-operation.html
Thanks it worked for me.:)
Finally after much searching, you answered my question, Mike !
Thanks !
There are a lot of people out in the web asking the same question.
When they and, (up till a few moments ago), myself included, try to “import” a simple text file into an Eclipse project, we were all receiving “file not found”.
Being new to Java I was amazed that this was such an “issue” for eclipse. I like Eclipse but something so fundamental, shouldn’t be so frustratingly hard. I guess the Devs are busy working on other more urgent issues and we cant complain as it is a free and in reality a good product.
Many thanks ! (c:\\testing) 🙂
somebody help this problem …
how to read this file 1
23
45
In your example, you should make sure to close the BufferedReader, otherwise the file may be lock not readable by some other process.
so
….
while ((sCurrentLine = br.readLine()) != null) {
System.out.println(sCurrentLine);
}
br.close();
…..
Example is updated, with new JDK7 example.
Excelente (Y)
sir i want jtree tool coding for netbeans 6.9
He he HI!
great work done by grat man
Di Shing