File - provides a view of a file and its enclosing folders

Basics

• A File object has no methods to access file contents. The purpose of a File object is to provide Java access to the name of the file and its enclosing folders.
  
  
• Because a the construction of a new File may not work out -- the indicated name may be invalid, programs that use File objects must indicate as part of the method main() definition that it may throw IOExceptions
  
  
  • public static void main( String[] args ) throws IOException
    

Important constructor for creating a File

• Suppose s is a String encoding the literal file name; e.g.,
  • String s = "mydata.txt";
    
    
• File f = new File( s );
  • Makes f a variable giving a File view of the file name stored by s.

How to set up a Scanner to read from a File

• Suppose f iis a File.
  
  
• Scanner stream = new Scanner( f );
  • Makes stream a variable giving a Scanner view of the file described by f.
    
    
  • The statement
    • int n = stream.nextInt();
      

  would read a number from file f.