How to wait in the same thread while file is being written to, to finish, so we can use it

Question

I have a file open and write situation that crashes with EOFException once in about 20-30 times, because the file is unavailable because some other process is writing to it.

Can I catch this exception, then somehow wait for the file write operation synchronously to end, so I can recurse the method?

File productJSON = getFileStreamPath("product" + "_" + getId() + ".json");
if (!productJSON.exists()) {
    productJSON = getFileStreamPath("product" + ".json");
}

InputStream jsonStringsFileInputStream;
try {
    jsonStringsFileInputStream = new FileInputStream(productJSON);

    HashMap<String, Map> that = new JSONToProductParser().convertThisToThat(jsonStringsFileInputStream);

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

not able to understand your Question can you please ellobrate — koutuk, Dec 02 '14 at 09:24
read/write operations on a file should be synchronized to avoid concurrency on a multithread app — jhamon, Dec 02 '14 at 09:25
Mark the File as synchronized. It will solve your problem in that case only one thread at a time will able to write on it. — Prakhar Asthana, Dec 02 '14 at 09:25
how do I mark the file as synchronized? wherever Im writing to it or wherever Im reading from it? — Kaloyan Roussev, Dec 02 '14 at 09:27

score 1 · Accepted Answer · edited May 23 '17 at 12:20

1

You can check the file for write access before opening it.This is done with the canWrite() method.

Oracle Docs - File # canWrite

Also check out this solved question. It deals with the synchronized attribute.

Solved Question - Synchronized

edited May 23 '17 at 12:20

Community

1
1

answered Dec 02 '14 at 09:27

cgew85

427
3
9

So what do I do if canWrite returns false? do I keep looping the check? So do I make all the methods that deal with this file synchronized? – Kaloyan Roussev Dec 02 '14 at 09:34
You can poll for a certain time or amount of tries,if it doesnt change its status throw an exception or handle it according to you needs.Regarding synchronization you might wanna read into this: https://docs.oracle.com/javase/tutorial/essential/concurrency/syncmeth.html – cgew85 Dec 02 '14 at 09:41

score -1 · Answer 2 · answered Dec 02 '14 at 09:28

-1

You can use a handler to introduce delays in your code.

final Handler handler=new Handler();
handler.postdelayed(new Runnable(){
@override
public void run(){
//Do something after 5 seconds....your code here
     }
},5000);

write your code within the run method

answered Dec 02 '14 at 09:28

archon92

447
3
13

This didnt work, because when I call the same method from within the handler, the rest of the code that started this method doesnt wait for the second iteration but goes on instead – Kaloyan Roussev Dec 02 '14 at 09:33

How to wait in the same thread while file is being written to, to finish, so we can use it

2 Answers2