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End of File on a Java BufferedReader

How do you sense if a BufferedReader in Java has reached the end of file? Like so many "things Java" it's easy enough to do ... once you find that vital method in the lists of thousands of calls!

There's no "eof"; there's no checking the input to see if you got nothing back after a read as that happens when at the end of file AND at embedded blank lines. But the ready method tells you if you have data available of not - and that's the one to use.

Here's a sample piece of code in Java to echo the first 12 lines of a file, and to count all the lines in the file too.

File myFile = new File ("access_log.xyz");
BufferedReader newFile = new BufferedReader(new FileReader(myFile));
int k=1;
while (true){
  if (! newFile.ready()) break;
  String next_line = newFile.readLine();
  if (k<12){
    System.out.println("Line Number:"+k+" - "+next_line);
    }
  k++;
  }

(written 2007-06-22)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
J713 - Java - More Input and Output
  [4420] Flexibility in input - read from file, web resource or keyboard - (2015-02-08)
  [4414] Java - converting an integer to a fixed length string - (2015-02-04)
  [4350] Keyboard reader for Java programming newcomers - (2014-12-12)
  [2420] Exceptions in Java - why and how - (2009-09-24)


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Comment: "//another way to do it ..."
2 unpublished comments pending on this page

Comment by himJ (published 2010-03-04)
//another way to do it
import java.io.*;
class bufferedDemoInput{
public static void main(String arg[]){
int ch=0;

//opens a file from the given unabsolute address;
File tempFile=new File("/HIMANSHUJ/myFile.txt");


try{

BufferedReader filer=new BufferedReader(new FileReader(tempFile));
//create an inputstream to the opened file

//detects end of file
while( (ch=filer.read())!= -1)
System.out.printf("%c",ch);


}
catch(FileNotFoundException e){
e.printStackTrace(System.err);
}
catch(IOException e){
e.printStackTrace(System.err);
}




}

} [#3478]

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