Question

I have a question regarding to the Java File class. When I create a File instance, for example,

File aFile = new File(path);

Where does the instance aFile store in the computer? Or it stores in JVM? I mean is there a temp file stored in the local disk?

If I have an InputStream instance, and write it to a file by using OutputSteam, for example

  File aFile = new File("test.txt");

  OutputStream anOutputStream = new FileOutputStream(aFile);

  byte aBuffer[] = new byte[1024];

  while( ( iLength = anInputStream.read( aBuffer ) ) > 0)
  {
    anOutputStream.write( aBuffer, 0, iLength);
  }

Now where does the file test.txt store?

Thanks in advance!

Answer 1

A File object isn’t a real file at all – it’s really just a filename/location, and methods which hook into the file system to check whether or not the file really exists etc. There’s no content directly associated with the File instance – it’s not like it’s a virtual in-memory file, for example. The instance itself is just an object in memory like any other object.

Creating a File instance on its own does nothing to the file system.

When you create a FileOutputStream, however, that does affect whatever file system you’re writing to. The File instance is relatively irrelevant though – you’d get the same effect from:

OutputStream anOutputStream = new FileOutputStream("test.txt");