Reference types - Data Structures and Problem Solving Using Java - page 57

figure 2.19
Program to list
contents of a file

1 import java.util.Scanner;
2 import java.io.FileReader;
3 import java.io.IOException;
4
5 public class ListFiles
6 {
7 public static void main( String [ ] args )
8 {
9 if( args.length == 0 )
10 System.out.println( "No files specified" );
11 for( String fileName : args )
12 listFile( fileName );
13 }
14
15 public static void listFile( String fileName )
16 {
17 Scanner fileIn = null;
18
19 System.out.println( "FILE: " + fileName );
20 try
21 {
22 fileIn = new Scanner( new FileReader( fileName ) );
23 while( fileIn.hasNextLine( ) )
24 {
25 String oneLine = fileIn.nextLine( );
26 System.out.println( oneLine );
27 }
28 }
29 catch( IOException e )
30 { System.out.println( e ); }
31 finally
32 {
33 // Close the stream
34 if( fileIn != null )
35 fileIn.close( );
36 }
37 }
38 }

listFile , we construct the FileReader object at line 22, and then use it to
construct a Scanner object, fileIn . At that point, reading is identical to what
we have already seen.
After we are done with the file, we must close it; otherwise, we could
eventually run out of streams. Note that this cannot be done at the end of the
try block, since an exception could cause a premature exit from the block.
Thus we close the file in a finally block, which is guaranteed to be started