It doesnot print the content the file

[abalfazl hossein]

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package fiedata;

import java.io.*;

/**
 *
 * @author Administrator
 */
public class Main {

    static final int[] prices = { 4500, 3000, 2500 };
    static final String[] books = { "JAVA","PHP","Mysql"};
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        // TODO code application logic here
       File f;
      f=new File("books.dat");
      if(!f.exists()){
      f.createNewFile();

      DataOutputStream out=null;
      out = new DataOutputStream(new
            BufferedOutputStream(new FileOutputStream("books.dat")));

      for (int i = 0; i < prices.length; i ++) {

           out.writeInt(prices[i]);
           out.writeUTF(books[i]);
           
          }

      DataInputStream in=null;
      in = new DataInputStream(new
            BufferedInputStream(new FileInputStream("books.dat")));
      int price;
      String book;

      try {
    while (true) {

        price = in.readInt();
        book= in.readUTF();
        System.out.format("saved in file %s  %i",book, price);

    }
} catch (EOFException e) {
}

    }

    }
}

This code does not print!

[Henry Wong]

You need to get into the habit of avoiding stuff like this...

} catch (EOFException e) {  
}  

If an error occurs, you will never know it since the application will just catch it and do nothing.

Henry

[Stephan van Hulst]

First of all, you don't have to check whether a file exists and create it separately. If you're using a FileOutputStream, it will automatically create the file. You can get rid of lines 25 and 26.

The problem is that you're forgetting to flush your output. The data you've written is still in memory.

[abalfazl hossein]

public class Main {

    static final int[] prices = { 4500, 3000, 2500 };
    static final String[] books = { "JAVA","PHP","Mysql"};
    public static void main(String[] args) throws IOException {
        // TODO code application logic here
             

      DataOutputStream out=null;
      out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("books.dat")));

      for (int i = 0; i < prices.length; i ++) {

           out.writeInt(prices[i]);
           out.writeUTF(books[i]);
           out.flush();
          }

      DataInputStream in=null;
      in = new DataInputStream(new BufferedInputStream(new FileInputStream("books.dat")));
      int price;
      String book;

      try {
           while (true) {

                     price = in.readInt();
                     book= in.readUTF();
                     System.out.format("saved in file %s  %i",book, price); }
       } 
      catch (EOFException e) {

                e.printStackTrace();
      }
      
    }
   }

still has problem:



run:

Exception in thread "main" java.util.UnknownFormatConversionException: Conversion = 'i'
at java.util.Formatter$FormatSpecifier.conversion(Formatter.java:2605)
at java.util.Formatter$FormatSpecifier.<init>(Formatter.java:2633)
at java.util.Formatter.parse(Formatter.java:2479)
at java.util.Formatter.format(Formatter.java:2413)
at java.io.PrintStream.format(PrintStream.java:920)
at fiedata.Main.main(Main.java:42)
Java Result: 1

[Henry Wong]

The stacktrace describes it all, you just need to learn how to read it.

abalfazl hossein wrote:
run:

Exception in thread "main" java.util.UnknownFormatConversionException: Conversion = 'i'
at java.util.Formatter$FormatSpecifier.conversion(Formatter.java:2605)
at java.util.Formatter$FormatSpecifier.<init>(Formatter.java:2633)
at java.util.Formatter.parse(Formatter.java:2479)
at java.util.Formatter.format(Formatter.java:2413)
at java.io.PrintStream.format(PrintStream.java:920)
at fiedata.Main.main(Main.java:42)
Java Result: 1

On line 42, of your program (Main.java), you are calling the format() method; And this method is encountering an "unknown format" specified as "%i". And if look at the JavaDocs...

http://download.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html

You will see that there is no such format.

Henry

[abalfazl hossein]

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package fiedata;

import java.io.*;

/**
 *
 * @author Administrator
 */
public class Main {

    static final int[] prices = { 4500, 3000, 2500 };
    static final String[] books = { "JAVA","PHP","Mysql"};
    public static void main(String[] args) throws IOException {
        // TODO code application logic here
             

      DataOutputStream out=null;
      out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("books.dat")));

      for (int i = 0; i < prices.length; i ++) {

           out.writeInt(prices[i]);
           out.writeUTF(books[i]);
           out.flush();
          }

      DataInputStream in=null;
      in = new DataInputStream(new BufferedInputStream(new FileInputStream("books.dat")));
      int price;
      String book;

      try {
           while (true) {

                     price = in.readInt();
                     book= in.readUTF();
                     System.out.format("saved in file %s  %d",book, price); }
       }
      catch (EOFException e) {

                e.printStackTrace();
      }

    }
   }

still has problem:

run:
java.io.EOFException
at java.io.DataInputStream.readInt(DataInputStream.java:375)
at fiedata.Main.main(Main.java:40)

[Henry Wong]

abalfazl hossein wrote:
still has problem:

run:
java.io.EOFException
at java.io.DataInputStream.readInt(DataInputStream.java:375)
at fiedata.Main.main(Main.java:40)

No offense, but isn't it time to, at least, try to solve the problem yourself? For example, did you even try to look up what an "EOF" means?

Henry

[Andrew Monkhouse]

BeForthrightWhenCrossPostingToOtherSites (other topic)

[abalfazl hossein]

I appreciate henry,But I need the answer.

and also Happy Christmas!! all!

[Mike Simmons]

Well if you need the answer, it will help a lot to ShowSomeEffort. This is beneficial two ways: it makes people here more willing to help you, and you might learn something.

As a hint: java.io.EOFException is a class in the standard Java library. It's documented like (almost) any standard Java class, in the Java API. In fact the forum software here has helpfully converted the phrase " java.io.EOFException " into a link. If you click on that link, you can get some clue as to what the problem is. If you don't understand it, all right, ask us for more help, and we're here. But please try to type something that shows you've done some work of your own (such as looking up java.io.EOFException to find out what it means).