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need guidance on this exercise

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posted 17 years ago

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Hello,

I am working on this exercise which requires me to do the following:

-Create a new servlet called RemoveItemsFromCart.java.

-Get it working with ReviewShoppingCart.java and AddToShoppingCart.java.

-You will need to edit ReviewShoppingCart.java to add another button that calls RemoveItemsFromCart.java

I have created the new servlet and the three are pasted below.

But my problem is that when I click the Remove button nothing happens.

I would be really thankful if someone guides me on this exercise. Causing me a lot of headache. Please advise if I am following an incorrect approach and if so what I should do.

Thanks in advance.
Ricky

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
 
public class AddToShoppingCart extends HttpServlet {
    
    public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException  {
        
        response.setContentType( "text/html" );
        PrintWriter aPW = response.getWriter();        
        aPW.println( "<HTML><HEAD><TITLE>Shopping Basket using Hidden Forms" + "</TITLE></HEAD><BODY>" );        
        aPW.println( "<FORM ACTION='ReviewShoppingCart' METHOD=GET>" );        
        aPW.println( "Add to Basket:<BR><BR>" );        
        aPW.println( "<INPUT TYPE='checkbox' NAME='items' VALUE='Socks  $4.0'>Socks  $4<BR>" );        
        aPW.println( "<INPUT TYPE='checkbox' NAME='items' VALUE='Shoes  $30.0'>Shoes  $30<BR>" );
        String items[] = request.getParameterValues( "items" );
        if ( items != null ) {            
            for ( int i=0; i < items.length; i++ ) {                
                aPW.println( "<INPUT TYPE=hidden NAME=items VALUE='" + items[i] + "'>" );                
            }
        }        
        aPW.println( "<BR><INPUT TYPE=submit VALUE='View Basket'>" );
    }
}

import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
 
public class RemoveItemsFromCart extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException  {
        
        response.setContentType( "text/html" );
        PrintWriter aPW = response.getWriter();
        aPW.println( "<HTML><HEAD><TITLE>Shopping Basket using Hidden Forms" + "</TITLE></HEAD><BODY>" );
        String newItems[] = request.getParameterValues( "items" );
        aPW.println( "Basket's contents:<BR><BR>" );
        if ( newItems != null ) {
            float count = 0;
            aPW.println( "<UL>" );
            for ( int i=0; i < newItems.length; i++ ) {
                int positionOfPound = newItems[i].indexOf( "$" ) + 1;
                String numberStr = newItems[i].substring( positionOfPound );
                System.out.println( "positionOfPound = " + positionOfPound );
                System.out.println( "numberStr = " + numberStr );
                float price = Float.parseFloat( numberStr );
                count = count + price;
                aPW.println( "<LI>" + newItems[i] + "<input type='checkbox' checked='checked' name='items' value='" + newItems[i] + "'" + " />");
            }
            aPW.println( "<BR><BR>Total:  $" + count );
            aPW.println( "</UL>" );
        }
        aPW.println( "<FORM ACTION='AddToShoppingCart' METHOD=GET>" );
        if ( newItems != null ) {
            for ( int i=0; i < newItems.length; i++ ) {
                aPW.println( "<INPUT TYPE=hidden NAME=items VALUE='" + newItems[i] + "'>" );
            }
        }
        aPW.println( "<BR><INPUT TYPE=submit VALUE='Add more items'>" );
        aPW.println( "</FORM></BODY></HTML>" );
        aPW.println( "<FORM ACTION='ReviewShoppingCart' METHOD=GET>" );
        if ( newItems != null ) {
            for ( int i=0; i < newItems.length; i++ ) {
                aPW.println( "<INPUT Type=hidden NAME=items VALUE='" + newItems[i] + "'>" );
            }
        }
        aPW.println( "<BR><INPUT TYPE=submit VALUE='Remove items'>" );
        aPW.println( "</FORM></BODY></HTML>" );
    }
    
}

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
 
public class ReviewShoppingCart extends HttpServlet {
    
    public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException  {
        
        response.setContentType( "text/html" );        
        PrintWriter aPW = response.getWriter();        
        aPW.println( "<HTML><HEAD><TITLE>Shopping Basket using Hidden Forms" + "</TITLE></HEAD><BODY>" );        
        String items[] = request.getParameterValues( "items" );
        aPW.println( "Basket's contents:<BR><BR>" );
        if ( items == null ) {            
            aPW.println( "No items in basket yet" );            
        } else {            
            float count = 0;            
            aPW.println( "<UL>" );            
            for ( int i=0; i < items.length; i++ ) {                
                int positionOfPound = items[i].indexOf( "$" ) + 1;                
                String numberStr = items[i].substring( positionOfPound );                
                System.out.println( "positionOfPound = " + positionOfPound );                
                System.out.println( "numberStr = " + numberStr );                
                float price = Float.parseFloat( numberStr );                
                count = count + price;                
                aPW.println( "<LI>" + items[i] + "<input type='checkbox' checked='checked' name='items' value='" + items[i] + "'" + " />");                  
            }            
            aPW.println( "<BR><BR>Total:  $" + count );            
            aPW.println( "</UL>" );
        }
        aPW.println( "<FORM ACTION='AddToShoppingCart' METHOD=GET>" );        
        if ( items != null ) {            
            for ( int i=0; i < items.length; i++ ) {                
                aPW.println( "<INPUT TYPE=hidden NAME=items VALUE='" + items[i] + "'>" );                
            }
        }        
        aPW.println( "<BR><INPUT TYPE=submit VALUE='Add more items'>" );        
        aPW.println( "</FORM></BODY></HTML>" );        
        aPW.println( "<FORM ACTION='RemoveItemsFromCart' METHOD=GET>" );        
        if ( items != null ) {            
            for ( int i=0; i < items.length; i++ ) {                
                aPW.println( "<INPUT TYPE=hidden NAME=items VALUE='" + items[i] + "'>" );                
            }
        }        
        aPW.println( "<BR><INPUT TYPE=submit VALUE='Remove items'>" );        
        aPW.println( "</FORM></BODY></HTML>" );
    }
}

[ April 10, 2007: Message edited by: Ricky James ]

Christophe Verré

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posted 17 years ago

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Aren't you allowed to use JSP ? Those servlets are a pain to read with all those html tags. Basically, you do some logic in your servlet and redirect to a JSP file to display the results. If you can use JSP in your assignment, clean those servlets first

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Ricky James

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Posts: 83

posted 17 years ago

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Originally posted by Satou kurinosuke:
Aren't you allowed to use JSP ? Those servlets are a pain to read with all those html tags. Basically, you do some logic in your servlet and redirect to a JSP file to display the results. If you can use JSP in your assignment, clean those servlets first

I am not allowed to use JSPs. But I think if you just copy and paste this code in your IDE, it becomes fairly clear and legible. I have the logic wrong somewhere but can't figure out what is wrong.

For example, I think that the 2 forms on 1 page are returning the hidden stuff.

Thanks
Ricky

Christophe Verré

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posted 17 years ago

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I am not allowed to use JSPs.

That's a pity

It's very hard to understand what's going on

I can see that you have before the second form. You should remove both body and html closing tags.

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Ricky James

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Posts: 83

posted 17 years ago

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Originally posted by Satou kurinosuke:

That's a pity It's very hard to understand what's going on

I can see that you have aPW.println( "</FORM></BODY></HTML>" ); before the second form. You should remove both body and html closing tags.

Thanks for the reply Satou.

I did what you suggested but the problem still exists.

I have a feeling that since I have a checkbox named items and also a hidden value named items. Now when I want to remove the items, only the hidden values gets transmitted, not the checkbox since there are in a different form. So there is no way of knowing which items have been unchecked.

But I am still confused as to what I should do.

Any suggestions?
Thanks
Ricky

Christophe Verré

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posted 17 years ago

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Your items checkboxes are not in a form, so they won't be sent.
What I suggest you to do is :
1. Make only one form
2. In the form, put the checkboxes, but no hidden items. You don't need them, because you only want the values of the checked items.
3. In the form, put the two submit buttons.
4. Use javascript's onClick() event to dynamically change the form's action
-> On pressing "Add more items", you set it to "AddToShoppingCart"
-> On pressing "Remove items", you set it to "RemoveItemsFromCart"

I'm surprised that you can't use JSP for this, as it's going to be a pain in the **** to output some Javascript from your servlet.

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