594: Mainline

You see strings and characters at work in the following program. This program differs from the one in Segment 570 in two key ways. First, the program reads strings from a file, as well as integers, and interprets the first character of those strings as a code letter. Second, the program uses the code letter to determine whether it should create a Movie instance or a Symphony instance:

import java.io.*; 
import java.util.*; 
public class Demonstrate { 
 public static void main(String argv[]) throws IOException { 
  Vector mainVector; 
  mainVector = Auxiliaries.readData("input.data");       
  for (Iterator i = mainVector.iterator(); i.hasNext();) {  
   System.out.println(((Attraction)i.next()).rating()); 
  }  
 } 
} 

import java.io.*; 
import java.util.*; 
public class Auxiliaries { 
 public static Vector readData(String fileName) throws IOException {              
  FileInputStream stream = new FileInputStream(fileName);  
  InputStreamReader reader = new InputStreamReader(stream); 
  StreamTokenizer tokens = new StreamTokenizer(reader); 
  Vector v = new Vector();  
  while (tokens.nextToken() != tokens.TT_EOF) { 
   String codeString = tokens.sval; 
   tokens.nextToken(); int x = (int) tokens.nval; 
   tokens.nextToken(); int y = (int) tokens.nval; 
   tokens.nextToken(); int z = (int) tokens.nval; 
   switch (codeString.charAt(0)) {  
     // First character indicates a movie: 
     case 'M': v.addElement(new Movie(x, y, z)); break; 
     // First character indicates a symphony: 
     case 'S': v.addElement(new Symphony(x, y, z)); break; 
   } 
  } 
  stream.close();  
  return v; 
 } 
}