CODEWITHSUNDEEP
javabinarybinaryfiles
Max Orozco
Max Orozco

Reputation: 33

Binary file I/O with custom object - Java

I am trying to write data to a binary file and am having difficulty. When I run this method I don't get any output to the file. Also when it comes to writing my "Date" object, I can't seem to find a write method that takes it as a parameter. The object consists of an int month, day, and year. How can I write it into a binary file properly?

Also, does "File" work for binary as well? I have only previously used it for regular .txt files and I'm not sure if it can be used the same way in this situation. Thanks!

Here is my write method:

private void writeBinary(){
    //String fileName = getUserInput();
    String fileTest = "BinaryMonster.bin";
    File file = new File(fileTest);
    DataOutputStream out;

    try{
       out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(file, true)));

       if(!(file.exists())){
           file.createNewFile();
           System.out.println("New file created...");
       }

       for(int i = 0; i < monsterAttacks.size(); i++){
           out.writeInt(monsterAttacks.get(i).getID());
           out.write(monsterAttacks.get(i).getDate()); //getting error
           out.writeUTF(monsterAttacks.get(i).getName() + monsterAttacks.get(i).getLocation() + monsterAttacks.get(i).getReporter());

       }

    } catch(IOException e) {
        e.printStackTrace();
    }
}

Upvotes: 0

Views: 251

Answers (1)

Rehan Javed
Rehan Javed

Reputation: 436

It is giving error because you are writing whole object of date into the file using DataOutputStream, which don't allow you to do that.

Write it in the form of String into the file. It will be better.

out.writeUTF(monsterAttacks.get(i).getDate().toString());

But if you want to save the whole object into the file, then you need to use ObjectOutputStream which write whole serialized objects into the file.

And it is better approach to flush and close the file.

out.flush();
out.close();

Upvotes: 1

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