Eof file in java

I tried to read lines of input until you reach EOF, then number and print all lines of content.

Sample Input
Hello world
I am a file
Read me until end-of-file.

Sample Output
1 Hello world
2 I am a file
3 Read me until end-of-file.

my code:
Scanner sc= new Scanner(System.in);
String msg= sc.next();
byte n=1;
n= sc.nextByte();
while(true){
System.out.println(n+" “+sc.hasNext(”/0"));
n++;
}

im getting error…can anyone help me with this

A few things I notice:

  1. Your loop never terminates - you have true for the while condition so that will never be false and you have no break statement.
  2. You are only calling hasNext without ever calling any of the next methods. As long as it has something, it will just keep returning true forever.
  3. You say you are trying to read a file, but you passed System.in to the Scanner so it will read the standard input at the command prompt and will never “end” because it will just request more input from the user when asked.
  4. If you did have a file as input to the scanner, calling hasNext("/0") is the wrong way to detect the end of the file. You would probably want the unqualified hasNext() method.

In general, you would read a file in Java using something more like java.io.FileReader (if reading printable characters - which we would probably wrap in a java.io.BufferedReader for efficiency) or java.io.FileInputStream (if reading raw bytes).

If you have a file with the contents you want to print called somefile.txt in the same directory where the Java binary is running, you can use this to read and print all of the lines until the end of the file:

try (var reader = new BufferedReader(new FileReader("somefile.txt"))) {
  reader.lines().forEach(System.out::println);
}
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Ohh okk… let me check and try again. thanks jason

Slight tweak to @jmrunkle’s solution…

I think you can do something like this if you need the line numbers:

try (var reader = new BufferedReader(new FileReader("somefile.txt"))) {
  int n = 1;
  reader.lines().forEach(line -> System.out.printf("%d %s%n", n++, line));
}
1 Like