Java Synchronize filewrite

Question

I have many threads that writes to a pool of files, I want to synchronize filewriter to avoid a dirty append.

Firstly I thought about this:

public synchronized void write(Ing ing) {
    File file=getFile(ing);
    FileWriter writer;
    writer=new FileWriter(file,true);
    // ...
}

but this synchronizes all writes, and I want to synchronize only writes on THE SAME file.

score 4 · Answer 1 · answered Jun 11 '14 at 14:35

4

To synchronize on each file, it seems that you can synchronize on the ing variable, which contains a reference to the file:

public void write(Ing ing) {
    synchronized(ing) {
        File file = getFile(ing);
        FileWriter writer = new FileWriter(file, true);
        ...
    }
}

answered Jun 11 '14 at 14:35

Jean Logeart

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"Ing" is an entity from a Dao object, another thread could get an equal object (but not the same object!) and write to the same file. Am I right? – Tobia Jun 11 '14 at 18:11
@Tobia If that's so, then what does `getFile()` do? If it returns the same File object, perhaps you can use that. – RealSkeptic Nov 03 '14 at 08:06
Yes, of course getFile() get a File object based on path String. Another time, there can be two different File object pointed to the same path... – Tobia Nov 03 '14 at 10:57

score 1 · Answer 2 · answered Dec 22 '20 at 10:31

1

By default FileWrite.append() is synchronized.

View in Writer.java.

answered Dec 22 '20 at 10:31

Albert Khang

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Java Synchronize filewrite

2 Answers2