import java.util.*;

/**
 * StringIntegerDemo
 * CS 2334, Section 001
 * Sept 23, 2002
 * <P>
 * This program demonstrates some of the problems with Collections.
 * </P>
 * @author unknown modified by dfh 19 Sep 2008
 * @version 1.0
 */
public class StringIntegerDemo {
    
    /** 
     * Default constructor.
     */
    public StringIntegerDemo() {
    }
    
    /**
     * This is the main method for this test program. Since this is a
     * simple test program, all of our code will be in the main method.
     * Typically this would be a bad design, but we are just testing out
     * some features of Java.
     * <P>
     * @param             args       Contains the command line arguments.
     */
    public static void main(String[] args) {
        // Create a list.
        List integerList = new ArrayList();
        
        // Create data to store in the list.
        Integer val1 = new Integer(3);
        Integer val2 = new Integer(10);
        
        String str1 = new String( "Hello World!" );
        String str2 = new String( "CS2334" );
        
        // Add the data to the list. Notice we can mix the data
        // types that we put into the list.  This can cause problems
        // if we are not careful.
        integerList.add( val1 );
        integerList.add( val2 );
        integerList.add( str1 );
        integerList.add( str2 );
        
        // Print the list.
        ListIterator itr = integerList.listIterator();
        
        System.out.println( "Contents of the list:" );
        while( itr.hasNext() ) {
            System.out.println( itr.next() );
        }
        
        // Increment the value of each integer in the list.
        itr = integerList.listIterator();
        
        while( itr.hasNext() ) {
        	//itr.next();  // Here we should be doing something to list elements
																				            // The following will not compile because the system
																				            // thinks that the element returned by next() is of
																				            // type Object.  It does not know that it should
																				            // be of type Integer.
            //itr.set( itr.next().intValue() + 1 );
            
            																				// This code will give a run time class cast exception
            //Integer i = (Integer)itr.next();
            //itr.set( new Integer( i.intValue() + 1 ) );
            
        																					// This code will work without errors.
            
            Object obj = itr.next();
            
            if( obj instanceof Integer ) {
               Integer j = (Integer)obj;
               itr.set( new Integer( j.intValue() + 1 ) );
            }
            
        }
        
        // Print the list.
        itr = integerList.listIterator();
        System.out.println( "Contents of the list:" );
        while( itr.hasNext() ) {
            System.out.println( itr.next() );
        }   
    }   
}