file.renameTo() test.

 

private void testFileIO(String fileName) {

  try {
   File file = new File(fileName);
   FileOutputStream fos = new FileOutputStream(file);
   byte[] byteArray = new byte[10];   
   byteArray[0] = 1;
   byteArray[4]=1;
   fos.write(byteArray);
   fos.close();   
   
   FileInputStream fis;
   fis= new FileInputStream(file);
   while (fis.available() > 0){
    System.out.print(fis.read());
   }
   fis.close();
   file.createNewFile();
   
   System.out.print("\n");
   File file2 = new File("654321.bin");
   //file2.createNewFile();
   //file2 should be created before as arg of renameTo()
   System.out.println(file.renameTo(file2));
   //renameTo may create the old file and the new file,transmit data from old to new.

   //old 0,new 0,success,old none,new created
   //old 1,new 0,success,old none,new created

//目标文件不存在时，总能成功，源文件被重命名

   //old 0,new 1,fail,old created,new null
   //old 1,new 1,fail,old created,new null

//目标文件存在时，总是失败，源文件在目录中存在并为原文件名(不论之前是否创建)

   System.out.println(file.getName());
   
   
   fis = new FileInputStream(file);
   while (fis.available() > 0){
    System.out.print(fis.read());
   }
   fis.close();
   
   
   //file对象中可读写数据而无须物理上的存在。
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

 }