Reading data from binary file (Java)?

Question

For a class I'm working on, I have to create a program that writes binary data to a file (based on user input) and then reads it to the console. This is done with two separate programs, one that processes data and one that gets user input. Whenever I try to list the contents of the file, it prints the last item over and over. What's the problem with my code?

Here's the relevant part of the program that processes user input and prints to the console:

String song = null;

try
{
    DataInputStream read = new DataInputStream(
    new FileInputStream( fileName ));

    while( read.available() > 0 )
    {
        song = process.readSong( fileName );
        System.out.println( song );
    }
}

catch( Exception e )
{
    System.out.println( "Error" );
}

Here's the relevant part of the program that processes data and reads it from the binary file:

public String readSong( String fileName )
{
    DataInputStream in = null;

    String sTitle;
    String sArtist;
    String sGenre;

    String song = null;

    try
    {
        in = new DataInputStream(
            new BufferedInputStream(
            new FileInputStream( fileName )));

        sTitle = in.readUTF();
        sArtist = in.readUTF();
        sGenre = in.readUTF();

        song = sTitle + "\t" + sArtist + "\t" + sGenre;

        in.close();
    }

    catch( Exception ex )
    {
        System.out.println( "Error" );
    }

    return song;
}

I would expect the while loop in the first code snippet to be infinite, since read is never read from, so it should always have data remaining. — clabe45
– clabe45, Commented Aug 8, 2017 at 16:43
You don't need to, and shouldn't use available(). It doesn't do what you think it does. — Kayaman
– Kayaman, Commented Aug 8, 2017 at 16:47

Sumeet · Accepted Answer · 2017-08-08 16:56:07Z

1

Your DataInputStream object is never modified, because DataInputStream in is local to function readSong().

You need to pass a reference of your DataInputStream object read in the function readSong().

So the call should be song = process.readSong( fileName , read ); and remove the local DataInputStream in from your function readSong()

answered Aug 8, 2017 at 16:56

Sumeet

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1 Comment

Becca Over a year ago

It worked! For whatever reason, though, only the first song listed in the binary file is getting printed to the console. Any idea why?

user2862544 · Accepted Answer · 2017-08-08 16:48:38Z

0

put while loop in readSong method then only it will read file line by line. while loop is not required in first method you just need to pass filename to readsong method.

answered Aug 8, 2017 at 16:48

user2862544

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