CODEWITHSUNDEEP
javabinaryfilesutfdataoutputstream
dave
dave

Reputation: 61

How to know number of bytes of a Binary File?

How to count number of bytes of this binary file (t.dat) without running this code (as a theoretical question) ? Assuming that you run the following program on Windows using the default ASCII encoding. 

public class Bin {
     public static void main(String[] args){
     DataOutputStream output = new DataOutputStream(
            new FileOutputStream("t.dat"));
     output.writeInt(12345);
     output.writeUTF("5678");
     output.close();
     }
}

Upvotes: 3

Views: 2633

Answers (1)

kshetline
kshetline

Reputation: 13700

Instead of trying to compute the bytes output by each write operation, you could simply check the length of the file after it's closed using new File("t.dat").length().

If you wanted to figure it out without checking the length directly, an int takes up 4 bytes, and something written with writeUTF takes up 2 bytes to represented the encoded length of the string, plus the space the string itself takes, which in this case is another 4 bytes -- in UTF-8, each of the characters in "5678" requires 1 byte.

So that's 4 + 2 + 4, or 10 bytes.

Upvotes: 2

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