Using Loop to Generate ArrayList

Question

In the code below, I am attempting to capture name, cost, and priority into an object. I use a for loop to create 7 objects and add each object to an ArrayList called itemData.

I do not think my code is retaining name, cost and priority into an item each time the loop is run. Any suggestions are greatly appreciated.

import java.util.*;


public class Main {

public static List<ItemData> itemData = new ArrayList<ItemData>();
public static void main(String[] args) {
    int i=0;
    //String name1;
    //int priority1; 
    //double cost1;

   String[] item  = new String[7];

   for (i=0; i<item.length; i++)  {
       Scanner keyboard = new Scanner(System.in);
       System.out.println("Enter item name " + i);
       String name = keyboard.next();
       Scanner keyboard2 = new Scanner(System.in);
       System.out.println("Enter the price of item " + i);
       double cost = keyboard2.nextDouble();
       Scanner keyboard3 = new Scanner(System.in);
       System.out.println("Enter Priority Number " + i);
       int priority = keyboard3.nextInt();

       ItemData grocItem = new ItemData(name, cost, priority);
       itemData.add(grocItem); // add grocery items to itemData ArrayList

   };

  System.out.println(item.name)

  // System.out.println(+ grocItem);
    }
    //How do I add grocItem to an Array list of other grocItems (6 grocItems from user input array item)
    //Main.itemData.add(groclist);


}


    Itemdata class:
    public class ItemData{
    public ItemData(String name, double cost, int priority){

// Main.groclist.add(grocItem);

How do you know they are not being retained? The code you posted doesn't compile, I'm assuming ItemData is defined somewhere and stores name, cost, priority in normal instance variables? You can get rid of the item array as well, you need to move the definition of grocItem into its place so that the System.out.println line will compile (an array does not have a name). — MilesHampson
– MilesHampson, Commented Jul 20, 2013 at 2:32

Saj · Accepted Answer · 2013-07-20 02:54:12Z

Your list is fine. It's just that you are trying to print the items of the list wrong way. You should do something like, say after your for loop-

for(ItemData someItem : itemData){
    System.out.println("\nName: " + someItem.name + "\tCost: " + someItem.cost + "\tPriority: " + someItem.priority);
}

You can improve your code by a long shot.

EDIT:

If you are willing to learn, here's a better version of what you are trying to do-

Let's define ItemData (Save ItemData below in ItemData.java file)-

public class ItemData {

    private String name;
    private double cost;
    private int priority;

    public ItemData(String name, double cost, int priority){
        this.name = name;
        this.cost = cost;
        this.priority = priority;
    }

    public void setName(String name){
        this.name = name;
    }

    public void setCost(double cost){
        this.cost = cost;
    }

    public void setPriority(int priority){
        this.priority = priority;
    }

    public String getName(){
        return this.name;
    }

    public double getCost(){
        return this.cost;
    }

    public int getPriority(){
        return this.priority;
    }
}

Now that we have our ItemData, we can use it like (Save GroceryProgram below in a file named GroceryProgram.java in the same directory as ItemData.java)-

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class GroceryProgram {

    private final static int GROC_SIZE = 6;
    private final List<ItemData> itemData = new ArrayList<ItemData>();

    private void setUpList(){

        Scanner keyboard = new Scanner(System.in);

        for (int i = 0; i < GROC_SIZE; i++)  {

               System.out.print("\nEnter item name (" + i + ") : ");               
               String name = keyboard.next();

               System.out.print("\nEnter the price of item (" + i + ") : ");
               double cost = keyboard.nextDouble();

               System.out.print("\nEnter Priority Number (" + i + ") : ");
               int priority = keyboard.nextInt();

               ItemData grocItem = new ItemData(name, cost, priority);
               itemData.add(grocItem); // add grocery items to itemData ArrayList
        }

        keyboard.close();
    }

    private void displayListItems(){

        for(ItemData someItem : itemData){
           System.out.println("\nName: " + someItem.getName() + "\tCost: " + someItem.getCost() + "\tPriority: " + someItem.getPriority());
        }

    }

    public static void main(String[] args) {

        GroceryProgram groProgram = new GroceryProgram();
        groProgram.setUpList();
        groProgram.displayListItems();

    }

}

To compile, do-

javac GroceryProgram.java

To execute-

java GroceryProgram

No questions?

wow. You just blew my mind. I will learn a lot going through this code.

Bohemian · Accepted Answer · 2013-07-20 03:58:49Z

Delete these lines - you're not using item so remove it entirely from your code:

String[] item  = new String[7];

System.out.println(item.name)

Now that you don't have item, fix the for loop:

for (i=0; i<7; i++) { // just code the loop to iterate 7 times

Next add a toString() method to ItemData, which is necessary for the following step to print readable output.

// return what you want - this is a reasonable example
public String toString() {
    return name + ", " + cost + " - priority " + priority;
}

Finally, print the list after the loop:

System.out.println(itemData};

That should pretty much fix up the problems you're having right now.

ruffner · Accepted Answer · 2013-07-20 02:23:15Z

0

String name = keyboard.next();

Is name ever more than two words? You might want to use keyboard.nextLine()

answered Jul 20, 2013 at 2:23

ruffner

161 bronze badge

Comments

Lokesh · Accepted Answer · 2013-07-20 02:33:47Z

0

This line is not correct "System.out.println(item.name)" . Item is an array.

Secondly you are not storing anything in array but in arraylist which is 'itemData'.

So try to fetch value from itemdata. For e.g: itemData.get(0).name

answered Jul 20, 2013 at 2:33

Lokesh

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