% java Concatenate Concatenate.java FileListEnumerator.java > Concatenate.out
% more Concatenate.out
/* 
 * An example taken from Sun's online textbook "The Java Tutorial"
 * at URL http://java.sun.com/tutorial/index.html
 *
 */

import java.io.*;

class Concatenate {

  public static void main( String[] args ) {

    // An Enumeration object:
    FileListEnumerator fileList = new FileListEnumerator( args );

    try {
      SequenceInputStream in = new SequenceInputStream( fileList );
      int c;
      while ( ( c = in.read() ) != -1 ) {
        System.out.write( c );
      }
      in.close();
    } catch ( IOException e ) {
      System.err.println( "Concatenate: " + e );
    }

  }

} // end class Concatenate

import java.util.*;
import java.io.*;

class FileListEnumerator implements Enumeration {

  String[] listOfFiles;
  int current = 0;

  FileListEnumerator( String[] listOfFiles ) {
    this.listOfFiles = listOfFiles;
  }

  public boolean hasMoreElements() {
    return ( current < listOfFiles.length );
  }

  public Object nextElement() {
    InputStream in = null;
    if ( !hasMoreElements() )
      throw new NoSuchElementException( "No more files!" );
    else {
      try {
        String nextElement = listOfFiles[ current++ ];
        in = new FileInputStream( nextElement );
      } catch ( FileNotFoundException e ) {
        System.out.println( "ListOfFiles: " + e );
      }
    }
    return in;
  }

} // end class FileListEnumerator