CODEWITHSUNDEEP
javafiletext
Syntic
Syntic

Reputation: 589

Using BufferedReader to read Text File

I'm having problems with using the BufferedReader

I want to print the 6 lines of a text file:

public class Reader {

public static void main(String[]args) throws IOException{
    
    FileReader in = new FileReader("C:/test.txt");
    BufferedReader br = new BufferedReader(in);
    
    while (br.readLine() != null) {
        System.out.println(br.readLine());
    }
    in.close();
    
}

Now from what I can gather every time I call the readLine() method it automatically advances to the next line.

So I can't use the condition br.readLine() != null since it'll already advance it one line and I get the output:

Line 2
Line 4
Line 6

What Condition do I use to check if there is still a new line in the text field?

Upvotes: 35

Views: 188422

Answers (9)

Bharathiraja
Bharathiraja

Reputation: 812

Use try with resources. this will automatically close the resources.

try (BufferedReader br = new BufferedReader(new FileReader("C:/test.txt"))) {
    String line;
    while ((line = br.readLine()) != null) {
        System.out.println(line);
    }
} catch (Exception e) {

}

Upvotes: 2

Subhojit Das
Subhojit Das

Reputation: 131

private void readFile() throws Exception {
      AsynchronousFileChannel input=AsynchronousFileChannel.open(Paths.get("E:/dicom_server_storage/abc.txt"),StandardOpenOption.READ);
      ByteBuffer buffer=ByteBuffer.allocate(1024);
      input.read(buffer,0,null,new CompletionHandler<Integer,Void>(){
        @Override public void completed(    Integer result,    Void attachment){
          System.out.println("Done reading the file.");
        }
        @Override public void failed(    Throwable exc,    Void attachment){
          System.err.println("An error occured:" + exc.getMessage());
        }
      }
    );
      System.out.println("This thread keeps on running");
      Thread.sleep(100);
    }

Upvotes: 1

NikhilP
NikhilP

Reputation: 1703

you can store it in array and then use whichever line you want.. this is the code snippet that i have used to read line from file and store it in a string array, hope this will be useful for you :)

public class user {
 public static void main(String x[]) throws IOException{
  BufferedReader b=new BufferedReader(new FileReader("<path to file>"));
  String[] user=new String[30];
  String line="";
  while ((line = b.readLine()) != null) {
   user[i]=line; 
   System.out.println(user[1]);
   i++;  
   }

 }
}

Upvotes: 0

sinisterrook
sinisterrook

Reputation: 364

or 

public String getFileStream(final String inputFile) {
        String result = "";
        Scanner s = null;

        try {
            s = new Scanner(new BufferedReader(new FileReader(inputFile)));
            while (s.hasNext()) {
                result = result + s.nextLine();
            }
        } catch (final IOException ex) {
            ex.printStackTrace();
        } finally {
            if (s != null) {
                s.close();
            }
        }
        return result;
}

This gets first line as well.

Upvotes: 0

Gokhan Demirhan
Gokhan Demirhan

Reputation: 1129

Try:

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

Upvotes: 0

Alya&#39;a Gamal
Alya&#39;a Gamal

Reputation: 5638

You read line through while loop and through the loop you read the next line ,so just read it in while loop 

 String s;
 while ((s=br.readLine()) != null) {
     System.out.println(s);
  }

Upvotes: 6

lichengwu
lichengwu

Reputation: 4307

Maybe you mean this:

public class Reader {

public static void main(String[]args) throws IOException{

    FileReader in = new FileReader("C:/test.txt");
    BufferedReader br = new BufferedReader(in);
    String line = br.readLine();
    while (line!=null) {
        System.out.println(line);
        line = br.readLine();
    }
    in.close();

}

Upvotes: 0

mthmulders
mthmulders

Reputation: 9705

You can assign the result of br.readLine() to a variable and use that both for processing and for checking, like so:

String line = br.readLine();
while (line != null) { // You might also want to check for empty?
    System.out.println(line);
    line = br.readLine();
}

Upvotes: 5

Jon Skeet
Jon Skeet

Reputation: 1500515

This is the problem:

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

You've got two calls to readLine - the first only checks that there's a line (but reads it and throws it away) and the second reads the next line. You want:

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

Now we're only calling readLine() once per loop iteration, and using the line that we've read both for the "have we finished?" and "print out the line" parts.

Upvotes: 80

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