readChar() method and EOF exception

Posted on 2002-03-21
Last Modified: 2010-05-18
I am a CS major and am trying to improve on my programming skills, but I have come across a roadblock. I am using the readChar() method to read characters one by one from a specified file and almost everything is going smoothly except that I am not sure on the most efficient way to let my program know it has reached the end of a file. I am trying to use the End Of File execption, but it still reads on forever. I pasted my code here for an illustration. Any pointers?

- Alex


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

     if (args.length < 1){
         System.out.println("Program syntax: java FileDemo FILE.XXX");

     DataInputStream in = new DataInputStream(
                          new FileInputStream(args[0]));

     InputStreamReader isr = new InputStreamReader(in);

     System.out.println("<<Start of file>>");

     try {
         char newChar = (char);
         while(true) {
          newChar = (char);
     } catch (EOFException e) { }
     System.out.println("<<End of file>>");    
Question by:alrav79
  • 3
  • 3

Accepted Solution

m_onkey_boy earned 50 total points
ID: 6887452
int c;
while ((c = != -1) {

Expert Comment

ID: 6887462
BTW - in your example, DataInputStream is not adding anything to your program other than overhead.

Author Comment

ID: 6887479
what do you mean overhead?
Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.


Author Comment

ID: 6887507
could have explained the process a litte more

Expert Comment

ID: 6888103
You didn't give me a chance to elaborate - you could have asked.


What I meant by overhead was that by using the datainputstream, you have instantiated an object tha was not needed.  Also, each call to read() is being passed up an extra method call ( calls, which in turn calls  Why not cut out the middleman?

As far as explaining the process - the code is self-explanatory.  I guess the part you should notice is that -1 is the EOF marker in a Java stream.

Author Comment

ID: 6888508
sorry, man, that was my fault....thanks for the explanation though; it was very helpful

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
oracle 11g 23 106
java jdbc batch example 8 41
sql import cannot be resolved jsp 3 45
ejb entity bean example issue 2 16
In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
Viewers learn about the scanner class in this video and are introduced to receiving user input for their programs. Additionally, objects, conditional statements, and loops are used to help reinforce the concepts. Introduce Scanner class: Importing…
This tutorial explains how to use the VisualVM tool for the Java platform application. This video goes into detail on the Threads, Sampler, and Profiler tabs.

840 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question