sorting between multiple arrays.

You will do well to search this forum for similar questions. This one has been asked and answered umpteen thousand times.

Also, you would do well to look at the sort method of the Arrays class which you can find here:

http://java.sun.com/j2se/1.5.0/docs/api/java/util/Arrays.html#sort(T[],%20java.util.Comparator)

and the Comparator interface which you can find here:

http://java.sun.com/j2se/1.5.0/docs/api/java/util/Comparator.html

If you have to implement your own bubble sort, it can be done and has been done. Again, search the forum for this.

Good luck.

Addendum: I just did a forum search on:

array bubble sort

and I got almost 300 forum hits.

Message was edited by:

petes1234

petes1234a at 2007-7-13 0:28:23 >

Thank you for your assistance.

The site that I found to be most helpful was the http://www.onjava.com/lpt/a/3286 site; however I am still experiencing problems. I have added code to the program as noted below:

public class Inventoryprogrampart3

{

/** Creates a new instance of Main */

/**

* @param args the command line arguments

*/

public static void main(String[] args)

{

// create Scanner to obtain input from command window

java.util.Scanner input = new java.util.Scanner( System.in );

double totalInventoryValue = 0;

NumberFormat nf = NumberFormat.getCurrencyInstance();

System.out.println(); // Displays a blank line

System.out.println( "Welcome to the Inventory Program - Part 2" ); // Display the string

System.out.println( "--" ); // displays a line of characters

System.out.println(); // Displays a blank line

System.out.println( "This program will output an office supply inventory" ); // Display the string

System.out.println( "listing that includes item numbers for the" ); // Display the string.

System.out.println( "inventoried products, the items product names, the" ); // Display the string.

System.out.println( "quantity of each product in stock, the unit price" ); // Display the string

System.out.println( "for each product, the total value of each products" ); // Display the string

System.out.println( "inventory, and a total value of the entire inventory." ); // Display the string

System.out.println(); // Displays a blank line

System.out.println( "*****************************************************" ); // Displays a line of characters

System.out.println(); // Displays a blank line

Product[] productArray = new Product[ 7 ]; // creates 7 product arrays

// adds data to the 7 arrays

productArray[0] = new Product();

productArray[0].setitemNumber(1);

productArray[0].setproductName ( "binder" );

productArray[0].setitemQuantity(15);

productArray[0].setitemPrice(1.5);

productArray[0].setinventoryValue(0);

productArray[1] = new Product();

productArray[1].setitemNumber(2);

productArray[1].setproductName( "paper" );

productArray[1].setitemQuantity(24);

productArray[1].setitemPrice(.95);

productArray[1].setinventoryValue(0);

productArray[2] = new Product();

productArray[2].setitemNumber(4);

productArray[2].setproductName( "pen" );

productArray[2].setitemQuantity(5);

productArray[2].setitemPrice(.25);

productArray[2].setinventoryValue(0);

productArray[3] = new Product();

productArray[3].setitemNumber(3);

productArray[3].setproductName( "marker" );

productArray[3].setitemQuantity(13);

productArray[3].setitemPrice(.5);

productArray[3].setinventoryValue(0);

productArray[4] = new Product();

productArray[4].setitemNumber(5);

productArray[4].setproductName( "pencil" );

productArray[4].setitemQuantity(28);

productArray[4].setitemPrice(.4);

productArray[4].setinventoryValue(0);

productArray[5] = new Product();

productArray[5].setitemNumber(7);

productArray[5].setproductName( "tape" );

productArray[5].setitemQuantity(14);

productArray[5].setitemPrice(1.65);

productArray[5].setinventoryValue(0);

productArray[6] = new Product();

productArray[6].setitemNumber(6);

productArray[6].setproductName( "staples" );

productArray[6].setitemQuantity(13);

productArray[6].setitemPrice(1.25);

productArray[6].setinventoryValue(0);

System.out.println( "Inventory listing prior to sorting by product name:" );

System.out.println(); // Displays a blank line

System.out.println( "Item #"+"\t"+"Product Name"+"\t"+"Stock"+"\t"+"Price"+"\t"+"Total Value"); // Displays a header line for the inventory array display

System.out.println(); // Displays a blank line

System.out.println( "--" ); // Displays a line of characters

System.out.println(); // Displays a blank line

for (int i=0; i<=6; i++)

{

Product products = productArray;

String productName = products.getproductName();

int itemNumber = products.getitemNumber();

int itemQuantity = products.getitemQuantity();

double itemPrice = products.getitemPrice();

double inventoryValue = products.getinventoryValue();

System.out.println( productArray.getitemNumber() +"\t"+ productArray.getproductName() +"\t"+"\t" + productArray.getitemQuantity() +"\t"+ nf.format(productArray.getitemPrice()) +"\t"+ nf.format(productArray.getinventoryValue()) );

}

Arrays.sort(productArray);

System.out.println( "--" ); // Displays a line of characters

System.out.println(); // Displays a blank line

System.out.println( "Inventory listing after being sorted by product name:" );

System.out.println(); // Displays a blank line

System.out.println( "Item #"+"\t"+"Product Name"+"\t"+"Stock"+"\t"+"Price"+"\t"+"Total Value"); // Displays a header line for the inventory array display

System.out.println(); // Displays a blank line

System.out.println( "--" ); // Displays a line of characters

for(int i=0; i <= 6; i++)

{

totalInventoryValue = totalInventoryValue + productArray.getinventoryValue(); // calculates the total value of the entire products inventory

System.out.println( productArray.getitemNumber() +"\t"+ productArray.getproductName() +"\t"+"\t"+ productArray.getitemQuantity() +"\t"+ nf.format(productArray.getitemPrice()) +"\t"+ nf.format(productArray.getinventoryValue()) );

}// end for

System.out.println(); // Displays a blank line

System.out.println( "The total value of the entire inventory is: " + nf.format(totalInventoryValue) ); // Displays the entire inventory value

System.out.println(); // Displays a blank line

System.out.println( "*****************************************************" ); // Displays a line of characters

} // end public static void main

}// end public class Inventoryprogrampart3 main

The following utilities have been set:

import java.io.*;

import java.text.*;

import java.util.Scanner;

import java.util.*;

import java.util.Arrays;

import java.util.ArrayList;

import java.util.Comparator;

The program compiles, however when I try to run the program I receive the following error (which outputs about 1/2 way through the program:

Exception in thread "main" java.lang.ClassCastException: Product can not be cast to java language comparable.

(along with a listing of other errors - I can't even get my cut and paste to work on my command prompt window).

I've tried about 50 different iterations and nothing seems to work.

Dman1a at 2007-7-13 0:28:23 >

> ...

> I can't see how anyone could learn java from my

> online institution.

>

> Sigh.

It's no problem at all if you read it carefully enough. The link you mentioned* explains exactly when, and why, a ClassCastException is thrown.

* http://www.onjava.com/lpt/a/3286

prometheuzza at 2007-7-13 0:28:23 >

> Could you recommend a Java programming consultant

> that I could talk to? I must not be reading the same

> things that you are, or we are not speaking the same

> "language", as I am not making any progress.

>

> If I could work with someone who could answer my

> questions, I feel that I could get the information

> that I need.

Ok, let me just quote the relevant part of the tutorial you (supposedly) read:

[...]

How do we sort these Person instances by age or by name? Using the java.util.Arrays class' sort method, as in:

Arrays.sort(persons);

will throw a ClassCastException.

You can, of course, write your own code to sort them using an algorithm such as quick sort, bubble sort, or others, but that's impractical. The easy solution is to implement the java.lang.Comparable interface.

Using the java.lang.Comparable Interface

Implement the Comparable interface to make class instances comparable. This interface has one method, compareTo, which determines how to compare two instances of the class. The signature of this method is:

public int compareTo(Object o)

The compareTo method accepts Object, so you can pass it an instance of any type. However, chances are that you want to make sure to compare two instances of the same type. It does not make sense to compare an elephant with an ant, for example. Therefore, you can throw a java.lang.ClassCastException if the argument of this method is not the same type as your class.

The compareTo method returns zero if the object passed is equal to this instance. It returns a positive integer or a negative integer if this object is greater or smaller than the passed object, respectively.

Let's have a look at the examples in Listing 4 and Listing 5. Listing 4 presents a Person class that implements the Comparable interface. Notice that a Person object is older if its age value is greater than the object compared. Listing 5 shows the Testing class that constructs four instances of the Person class and sorts them by age. Both classes in Listings 4 and 5 reside in the comparable.ex01 package.

Listing 4: The Person Class That Implements the Comparable Interface

package comparable.ex01;

class Person implements Comparable {

private String firstName;

private String lastName;

private int age;

// prometheuzz: removed some obvious methods here

public int compareTo(Object anotherPerson) throws ClassCastException {

if (!(anotherPerson instanceof Person))

throw new ClassCastException("A Person object expected.");

int anotherPersonAge = ((Person) anotherPerson).getAge();

return this.age - anotherPersonAge;

}

}

[...]

Now look at your own object that you're trying to compare. In what ways does it differ from the Person class in the example?

prometheuzza at 2007-7-13 0:28:23 >