parameter of directorySize()

[komomo]

What is the parameter of this method? In the book I read, no parameter is used for that method.
public long directorySize()

[ektasrv]

As per the API doc it takes a boolean;

directorySize


public long directorySize(boolean includeSubDirs)
throws java.io.IOException

Determines the size in bytes on a file system of all of the files that are contained in a directory.

Returns:
The size in bytes occupied by the files included in the directory, or -1 if the directory does not exist or is not accessible.

Throws:
java.io.IOException - if the method is invoked on a file.
java.lang.SecurityException - if the security of the application does not have read access for the directory.
IllegalModeException - if the application does have read access to the directory but has opened the connection in Connector.WRITE mode.
ConnectionClosedException - if the connection is closed.