java - Get the file size in android sdk?

Question

I have a problem getting the size of a file. I have the following code:

File file = new File("/sdcard/lala.txt");
long length = file.length();

And always length is zero, yes zero.

I am using Android SDK (not sure what version), the code is running inside an Activity, I have created an sdcard.

Perhaps it is a permission issue? Is there anything I am missing?

Answer 1

The File.length() method returns the following according to the javadoc:

"The length, in bytes, of the file denoted by this abstract pathname, or 0L if the file does not exist. Some operating systems may return 0L for pathnames denoting system-dependent entities such as devices or pipes."

As you can see, zero can be returned:

• if the file exists but contained zero bytes.
• if the file does not exist, or
• if the file is some OS-specific special file.

My money is on the second case; i.e. that you have the wrong filename / pathname. Try calling File.exists() on the filename to see what that tells you. The other two cases are possible too, I guess.

(For the record, most /proc/... files on a Linux-based system also have an apparent file size of zero. And Android is Linux based.)