From single-threaded to multi-threaded Java code

[ahmed1308]

Hello.

I would like to know how to turn the following Java code into a multi-threaded one where a thousand threads are created to each write one integer into the output file:

public void writeIntegersToFile () {
    File outputFile = new File("FirstThousandIntegers.txt");
    try {
        FileWriter out = new FileWriter(outputFile);
        PrintWriter writer = new PrintWriter(out);
        for (int p=0; p<1000; p++)
                writer.println(p);
        out.close();
    }
    catch (IOException e) {
        System.out.println("Couldn't open " + outputFile.getName());
    }        
}

[Norm]

What is the purpose of making that change?
There will be a contention problem when more than one thread tries to write to the same file at the same time. For them to not get in each others way, each thread will have to wait its turn. The end result will take much longer than doing it on one thread.

One way to use 1000 threads would be to create the threads one at a time that write its number to the file and exits before the next thread is created.