java多线程读写同一个文件

Question

      同一个文件可以同时被一个线程读另一个线程写吗？

Answer 1

如果有一个线程正在读文件，这时又有另个一个线程想来写这个文件 会报错吗?
答案是不会。
请运行以下的代码 就知道了
[code="java"]package org.sse.test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class IO {

/**
 * @param args
 */
public static void main(String[] args) {
    new IO().test();
}

private void test() {
    ReadThead rt = new ReadThead();
    Thread t1 = new Thread(rt, "ReadThead");
    WriteThead wt = new WriteThead();
    Thread t2 = new Thread(wt, "WriteThead");
    t1.start();
    t2.start();
}

protected class WriteThead implements Runnable {

    @Override
    public void run() {
        try {
            File f = new File("D:\\A.txt");
            FileOutputStream fos = new FileOutputStream(f);
            byte[] b = "hello".getBytes();
            while (true) {
                fos.write(b);
                fos.flush();
                Thread.sleep(1000);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }

}

protected class ReadThead implements Runnable {

    @Override
    public void run() {
        try {
            File f = new File("D:\\A.txt");
            FileInputStream fis = new FileInputStream(f);
            int readData;
            while (true) {
                readData = fis.read();
                if (readData == -1) {
                    Thread.sleep(1000);
                } else {
                    System.out.println(readData);
                }
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

}
[/code]