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Revision as of 00:13, 9 April 2010
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Problem
Write a program create a simple grocery list. Prompt the user for the number of items in the list. Use parallel arrays to store the item names and quantities. Then print the list of items and a count of the number of items
Example Output
Grocery List
------------
1 bacon
12 eggs
4 apples
17 items
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More with Arrays
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Solution
First, prompt the user for the number of items:
String input; //temp variable for dialog input
int listSize = 0; //the number of items for the grocery list, default 0
input = JOptionPane.showInputDialog("Input length:");
listSize = Integer.parseInt(input);
Now that we have the number of items, listSize, we need to get the items and quantities.
//Create arrays for list items and quantity
String[] groceryList = new String[listSize];
int[] groceryQuantity = new int[listSize];
//prompt for input listSize times
for( int i = 0; i < groceryList.length; i++ )
{
//get the name of the item and
groceryList[ i ] = JOptionPane.showInputDialog("Item name");
input = JOptionPane.showInputDialog("How many " + groceryList[ i ] + "?" );
groceryQuantity[ i ] = Integer.parseInt( input );
}
Last step is to print the list out. We will use the loop for printing to sum the quantities.
int itemCount = 0; //sum of the quantities of the items
//Print a header for the list
System.out.println( "Grocery List" );
System.out.println( "------------" );
//loop through and print out the list items
for( int i = 0; i < groceryList.length; i++ )
{
System.out.println( groceryQuantity[ i ] + " " + groceryList[ i ] );
itemCount = itemCount + groceryQuantity[ i ];
}
System.out.println( "\n" + itemCount + " items.");
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Code
Solution Code
import javax.swing.JOptionPane;
public class grocery {
public static void main( String[] args )
{
String input; //temp variable for dialog input
int listSize = 0; //the number of items for the grocery list, default 0
input = JOptionPane.showInputDialog("Input length:");
listSize = Integer.parseInt(input);
//Create arrays for list items and quantity
String[] groceryList = new String[listSize];
int[] groceryQuantity = new int[listSize];
//prompt for input listSize times
for( int i = 0; i < groceryList.length; i++ )
{
//get the name of the item and
groceryList[ i ] = JOptionPane.showInputDialog("Item name");
input = JOptionPane.showInputDialog("How many " + groceryList[ i ] + "?" );
groceryQuantity[ i ] = Integer.parseInt( input );
}
int itemCount = 0; //sum of the quantities of the items
//Print a header for the list
System.out.println( "Grocery List" );
System.out.println( "------------" );
//loop through and print out the list items
for( int i = 0; i < groceryList.length; i++ )
{
System.out.println( groceryQuantity[ i ] + " " + groceryList[ i ] );
itemCount = itemCount + groceryQuantity[ i ];
}
System.out.println( "\n" + itemCount + " items.");
}
}
Once I have a working example I like to go a step further and simplify the code<br>
<ol>
<li>The loop for prompting the user and the loop for printing the list can be combined.</li>
<li>By passing the String returned by JOptionPane to Integer.parseInt you can remove the input variable.</li>
</ol>
import javax.swing.JOptionPane;
public class grocery2 {
public static void main( String[] args )
{
int listSize = 0; //the number of items for the grocery list, default 0
int itemCount = 0; //sum of the quantities of the items
listSize = Integer.parseInt( JOptionPane.showInputDialog("Input length:") );
//Create arrays for list items and quantity
String[] groceryList = new String[listSize];
int[] groceryQuantity = new int[listSize];
//Print a header for the list
System.out.println( "Grocery List\n------------" );
for( int i = 0; i < listSize; i++ )
{
//get the name of the item and
groceryList[ i ] = JOptionPane.showInputDialog("Item name");
groceryQuantity[ i ] = Integer.parseInt( JOptionPane.showInputDialog("How many " + groceryList[ i ] + "?" ) );
//print the item on quantity to console
System.out.println( groceryQuantity[ i ] + " " + groceryList[ i ] );
//add the most recent quantity to the item count
itemCount = itemCount + groceryQuantity[ i ];
}
System.out.println( "\n" + itemCount + " items.");
}
}
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