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Help on logic

Posted on 2001-06-06
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Last Modified: 2010-03-31
I have a string which have the product code|quantity|@price
and separate by a "#" for each set. Example:

A123|20|2.99#B444|9|1.20#.........and so on.

but now, the user will add several set of string to this existing string, and the product code will be duplicate, so I would like to add the quantity for the same product code. For example the user input the:

N934|18|6.00#V245|6|0.00#A123|10|2.99#......

so the final output string will be:
A123|30|2.99##B444|9|1.20#N934|18|6.00#V245|6|0.00

Please help with sample code for how to do it. Thanks !!
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Question by:clo1
9 Comments
 
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Expert Comment

by:LDC
ID: 6159197
You can use StringTokenizer to cut your string in bits between the #, then between the |.
You then get lists of strings for item/price/quantity.
Store the items in a Hashtable, convert the quantity string to a int (Integer.parseInt if I remember well). Then put the Integer into the Hashtable as a value if there was no value, else sum the values to get the new Integer.
Now, what if your user types A123|10|29.9# which is a different price? How do you know which price is correct?
Your user should probably never have to type strings like that.
Why don't you give them a panel where they put a list of article/quantity? You could more easily generate your String afterwards.
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Expert Comment

by:TimYates
ID: 6159205
What you want is a class like this:

class Product
{
  public String id ;
  public int amount ;
  public double price ;

  public Product( String prodString )
  {
    StringTokenizer st = new StringTokenizer( "|" ) ;
    int pos = 1 ;
    while( st.hasMoreTokens() )
    {
      String element = st.nextToken() ;
      switch( pos )
      {
        case 1 :
          id = element ;
          break ;
        case 2 :
          amount = Integer.parseInt( element ) ;
          break ;
        case 3 :
          price = Double.parseDouble( element ) ;
          break ;
      }
      pos++ ;
    }
  }

  public boolean isEqual( Object o )
  {
    if( o instanceof Product )
    {
      return ((Product)o).id.equals( this.id ) ;
    }
    return false ;
  }

  public String toString()
  {
    return id + "|" + amount + "|" + price ;
  }

  public addAmount( Product p )
  {
    this.amount += p.amount ;
  }
}

Create a Vector (call it v).

then use a String tokenizer (like above) to split the string at the "#" characters, and create a product by calling the constructor with this string (call it p)...

then, if v.indexOf( p ) finds the product with that id already exists in the vector (returns a position grater than -1 -- call that pos )

do:

((Product)v.elementAt( pos )).addAmount( p ) ;

Then at the end, step through all of the elements in your vector, and output them with a hash between them...

String str = "" ;
for( int i = 0 ; i < v.size() ; i++ )
{
  str += ((Product)v.elementAt( i )).toString() ;
  if( i < v.size() - 1 ) str += "#" ;
}

Good luck...

Tim.
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Expert Comment

by:DanVan
ID: 6159238
Ah, I see a load of people have answered, but here goes.
This should demo the idea of having a system that should be flexible enough to allow you to change product prices easily, build a nice GUI on it, whatever you want.
Use Tim's post to see how to parse the strings to extract the info if needed.

Good luck
Dan

just paste the below into a file called "Test.java" and run it to see if it is the sort of thing you are looking for.
-------------------
import java.util.*;

public class Test {
     public static void main(String[] args) {
          Orders o = new Orders();
          Products p = new Products();
         
          p.add( new Product("A0123", 2.2f) );
          p.add( new Product("B0123", 1.2f) );
          p.add( new Product("C0123", 0.2f) );
         
          //retrieve the product for a given string:
          Product prod;
          prod = p.find("A0123");
          o.addOrder(prod, 3);

          prod = p.find("B0123");
          o.addOrder(prod, 1);

          prod = p.find("A0123");
          o.addOrder(prod, 2);
         
          prod = p.find("XXXX");
          if (prod == null) {
               System.out.println("Invalid product entered");
          }else {
               o.addOrder(prod, 3);
          }
         
          //Print the orders as one long string
          System.out.println(o);          
     
          //change the price of one of the products:
          prod = p.find("B0123");
          prod.price = 5.5f;
         
          //add another order:
          prod = p.find("B0123");
          o.addOrder( prod, 10 );

          //Print the orders as one long string
          System.out.println(o);          
     
     }
     
     
}

class Product {
     public String code;
     public float price;
     
     Product(String code, float price) {
          this.code = code;
          this.price = price;
     }
}

class Products {
     Hashtable allProducts = new Hashtable();
     
     public void add( Product p ) {
          allProducts.put(p.code, p );
     }
     
     public Product find( String code ) {
          Product p = (Product)allProducts.get( code );
          return p;
     }
}


class Orders {
     Hashtable allOrders = new Hashtable();
     
     public void addOrder(Product prod, int quantity) {
          int num = 0;
          Integer numInt = (Integer)allOrders.get(prod);
          if (numInt != null) {
               num = numInt.intValue();
          }
          num += quantity;
          allOrders.put(prod, new Integer(num));
     }
     
     public int getOrder(Product prod) {
          int num = 0;
          Integer numInt = (Integer)allOrders.get(prod);
          if (numInt != null) {
               num = numInt.intValue();
          }
          return num;    
     }
     
     public String toString() {
          int max = allOrders.size() - 1;
          StringBuffer buf = new StringBuffer();
          Iterator it = allOrders.entrySet().iterator();

          while (it.hasNext()) {
              Map.Entry e = (Map.Entry) (it.next());
               Product prod = (Product)e.getKey();
              buf.append(prod.code +"|"+ e.getValue() +"|"+ prod.price +"#");
          }
          return buf.toString();
     }
}
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LVL 3

Accepted Solution

by:
chrisos earned 100 total points
ID: 6159247
Yeah, more code!

Chrisos

/////////////////////////////////////////////////////

package com.wintermuteis;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.StringTokenizer;
import java.util.Arrays;

public class Summation extends Object {

     private static class Product extends Object {
          String name = null;
          int quantity = 0;
          float cost = 0f;

          Product(String name, int initialQuantity, float cost) {
               this.name = name;
               this.quantity = initialQuantity;
               this.cost = cost;
          }

          void incrementQuantity( int additionalQuantity ) {
               quantity += additionalQuantity;
          }
     }

     public static String summarize(String source) {
          Hashtable allProducts = new Hashtable();
          StringTokenizer products = new StringTokenizer(source, "#");
          StringTokenizer values = null;
          String currentProduct = null;
          String currentValue = null;
          String name = null;
          int quantity = 0;
          float cost = 0f;
          int valueCounter = 0;
          while( products.hasMoreTokens() ) {
               currentProduct = products.nextToken();
               values = new StringTokenizer(currentProduct, "|");

               name = null;
               quantity = 0;
               cost = 0f;
               valueCounter = 0;

               while( values.hasMoreTokens() ) {
                    currentValue = values.nextToken();
                    switch( valueCounter ) {
                         case 0:
                              name = currentValue;
                              break;
                         case 1:
                              quantity = Integer.parseInt(currentValue);
                              break;
                         case 2:
                              cost = Float.parseFloat(currentValue);
                              break;
                    }
                    valueCounter++;
               }
               if( !allProducts.containsKey(name) ) {
                    Product newProduct = new Product(name, quantity, cost);
                    allProducts.put(name, newProduct);
               }
               else {
                    Product existingProduct = (Product)allProducts.get(name);
                    existingProduct.incrementQuantity(quantity);
               }
          }

          StringBuffer result = new StringBuffer();
          Enumeration keys = allProducts.keys();
          String[] keyNames = new String[allProducts.size()];
          int count = 0;
          while( keys.hasMoreElements() ) {
               keyNames[count] = (String)keys.nextElement();
               count++;
          }
          Arrays.sort(keyNames);

          Object key = null;
          Product outProduct = null;
          for( int i = 0; i < keyNames.length; i++ ) {
               key = keyNames[i];
               outProduct = (Product)allProducts.get(key);
               result.append(outProduct.name+"|"+outProduct.quantity+"|"+outProduct.cost+"#");
          }
          result.delete(result.length()-1,result.length()-1);
          return result.toString();;
     }

     public static void main(String[] args) {
          String test = "A123|20|2.99#B444|9|1.20";
          System.out.println("Test: "+test+" -> "+summarize(test));
          test = "A123|20|2.99#B444|9|1.20#N934|18|6.00#V245|6|0.00#A123|10|2.99";
          System.out.println("Test: "+test+" -> "+summarize(test));
     }
}
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Expert Comment

by:chrisos
ID: 6159293
Mine does the decode, summarisation and encode, does than mean I'm the winnder? :)
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Expert Comment

by:TimYates
ID: 6159524
My Product class is more contained ;-P

Hee hee!

Tim
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Expert Comment

by:TimYates
ID: 6159531
;-)
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Expert Comment

by:chrisos
ID: 6160736
Mine demonstrates encapsulation using inner classes!

(Although in all fairness I could have added a toString() to the inner class)

:P
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Expert Comment

by:TimYates
ID: 6162969
Oh well, you win ;-)
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