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javarandomaccessfile

RandomAccessFile: Getting Java.io.EOFException


I have the code:

junk.writeUTF("Jim");
junk.writeInt(9304029);
junk.writeUTF("England");

junk.writeUTF("Bob");
junk.writeInt(99291933);
junk.writeUTF("Canada");

junk.seek(12);
String name = junk.readUTF();
int number = junk.readInt();
String city = junk.readUTF();

When I run it I am getting the error message saying it's null. I get why this is happening but how do I know which byte to seek to so I can read the data for Bob? seek(12) is giving null.


Solution

  • int isn't 2 bytes, it's 4. And writeUTF writes a 2-byte length prefix, so the total length is supposed to be 18.

    If we consider the offsets of each piece of data:

                Offset
    UTF length  0
    Jim         2
    9304029     5
    UTF length  9
    England     11
    

    When you pass in 12, it will try to read a UTF string using ng as the length, which is 28263, which is obviously a bit longer than your file.