Java IndexOutOfBound

**maple1100** · March 16th, 2013, 06:57 PM

Could someone help me with fixing this indexoutofbound error? The error is occuring at
"s += catalog.get(i).toString() + "," + catalog.get(i).getSKU() + ": " + b.getContents().get(i)+ "\n" ;"

java.lang.IndexOutOfBoundsExceptions: Index 1 Size 1 - Is the error I am getting. Thanks

import java.util.*;
public class Media
{   
    public static ArrayList<MusicMedia> MakeMusicCatalog(int size)
    {
        String[]titles = 
            {
                "Greatest Hits volume 1", "Greatest Hits Volume 2",
                "The Best of", "Love Songs",
                "The Early Years", "The Later Years"
            };
        String [] artists = 
            {
                "Michael Jackson", "Eminem",
                "The Beatles", "Shania Twain",
                "Limp Bizkit"
            };
        ArrayList<MusicMedia> a = new ArrayList<MusicMedia>();
        Random rn = new Random();
        for (int i = 0 ; i < size; i++)
        {
            MusicMedia m ;
 
            int mediatype = rn.nextInt(3);
            String title = titles[rn.nextInt(titles.length)];
            String artist = artists[rn.nextInt(artists.length)];
            String sku = "1234-"+ i;
            if(mediatype == 0 )
                m = new CompactDisk (title, artist, sku);
            else if(mediatype == 1)
                m = new DigitalVideoDisk(title,artist,sku);
            else 
                m = new CassetteTape(title,artist,sku);
 
            a.add(m);
            }
            return a;
        }
 
    public static String lookupMedia(ArrayList<MusicMedia> catalog, String sku)
    {   
        for(MusicMedia m : catalog)
        {
            if(m.getSKU().equalsIgnoreCase(sku))
            {
                return sku;
            }
        }
        return "SKU not in catalog";
    }
 
    public static String detailedInventory(ArrayList<MusicMedia> catalog, ArrayList<Bin> warehouse)
    {
        String s = "";
        for(Bin b : warehouse)
        {
            s += "Bin " + b.getName()+ ":\n";
            for(int i = 0 ; i < (warehouse.size()); i++)
            {
                s += catalog.get(i).toString() + "," + catalog.get(i).getSKU() + ": " + b.getContents().get(i)+ "\n" ;
            }
            s += "\n";
        }
        return s;
    }
 
    public static void main(String[]args)
    {
      ArrayList<MusicMedia> catalog = MakeMusicCatalog( 10 );
      ArrayList<Bin> warehouse = new ArrayList<Bin>();
      Bin a = new Bin( "A" );
      Bin b = new Bin( "B" );
      warehouse.add( a );
      warehouse.add( b );
      a.add( new BinItem( "1234-0", 500 ) );
      a.add( new BinItem( "1234-1", 25 ) );
      a.add( new BinItem( "1234-2", 7720 ) );
      b.add( new BinItem( "1234-3", 1000 ) );
      System.out.println( detailedInventory( catalog, warehouse));
 
    }
}

**Norm** · March 16th, 2013, 07:01 PM

java.lang.IndexOutOfBoundsExceptions: Index 1 Size 1

If the array has a size of 1 then the maximum index is 0.

Check the logic to make sure the index does not go past the array length-1

**maple1100** · March 16th, 2013, 07:08 PM

That what I was thinking too. Since the size of warehouse is only 4, the maximum index would be 3. I figured the error is at "for(Bin b : warehouse)" since warehouse is 4 and it would result in the inner for loop running 4 time but the index of warehouse should be 3, am I correct? Thanks

**Norm** · March 16th, 2013, 07:10 PM

Which get() is causing the error? Look at the size of the collections connected to the get() methods being called.

**maple1100** · March 16th, 2013, 07:15 PM

"b.getContents().get(i)" is causing the error because only 4 ArrayList is created but the for loop is calling for < catalog.size() which is 10.

**Norm** · March 16th, 2013, 07:20 PM

It doesn't make sense to use a index that is past the end. The code needs to be changed so the index does not go past the end.

**maple1100** · March 16th, 2013, 08:19 PM

I edited the code a little and here is the new code

import java.util.*;
public class Media
{   
    public static ArrayList<MusicMedia> MakeMusicCatalog(int size)
    {
        String[]titles = 
            {
                "Greatest Hits volume 1", "Greatest Hits Volume 2",
                "The Best of", "Love Songs",
                "The Early Years", "The Later Years"
            };
        String [] artists = 
            {
                "Michael Jackson", "Eminem",
                "The Beatles", "Shania Twain",
                "Limp Bizkit"
            };
        ArrayList<MusicMedia> a = new ArrayList<MusicMedia>();
        Random rn = new Random();
        for (int i = 0 ; i < size; i++)
        {
            MusicMedia m ;
 
            int mediatype = rn.nextInt(3);
            String title = titles[rn.nextInt(titles.length)];
            String artist = artists[rn.nextInt(artists.length)];
            String sku = "1234-"+ i;
            if(mediatype == 0 )
                m = new CompactDisk (title, artist, sku);
            else if(mediatype == 1)
                m = new DigitalVideoDisk(title,artist,sku);
            else 
                m = new CassetteTape(title,artist,sku);
 
            a.add(m);
            }
            return a;
        }
 
    public static String lookupMedia(ArrayList<MusicMedia> catalog, String sku)
    {   
        for(MusicMedia m : catalog)
        {
            if(m.getSKU().equalsIgnoreCase(sku))
            {
                return sku;
            }
        }
        return "SKU not in catalog";
    }
 
    public static String detailedInventory(ArrayList<MusicMedia> catalog, ArrayList<Bin> warehouse)
    {
        String s = "";
        for(int i = 0  ; i < warehouse.size();i++)
        {
            s += "Bin " + warehouse.get(i).getName()+ ":\n";
            s += catalog.get(i) + "," + warehouse.get(i).getContents()+ "\n" ;
            s += "\n";
        }
        return s;
}   
 
 
 
    public static void main(String[]args)
    {
      ArrayList<MusicMedia> catalog = MakeMusicCatalog( 10 );
      ArrayList<Bin> warehouse = new ArrayList<Bin>();
      Bin a = new Bin( "A" );
      Bin b = new Bin( "B" );
      warehouse.add( a );
      warehouse.add( b );
      a.add( new BinItem( "1234-0", 500 ) );
      a.add( new BinItem( "1234-1", 25 ) );
      a.add( new BinItem( "1234-2", 7720 ) );
      b.add( new BinItem( "1234-3", 1000 ) );
      System.out.println( detailedInventory( catalog, warehouse));
 
    }
}

import java.util.*;
public class Bin
{
    private String myName;
    private ArrayList<BinItem> myContents ;
 
    public Bin(String name)
    {
        myName = name;
        myContents =  new ArrayList<BinItem>();
    }
 
    public String getName()
    {
        return myName;
    }
 
    public void add(BinItem b)
    {
          myContents.add(b);
    }
 
        public ArrayList<BinItem> getContents()
    {
        return myContents;
    }
    public String toString()
    {
        String s = "Bin "+ myName + ":\n";
        for (BinItem b : myContents)
            s += b + "\n";
 
        return s;
    }
}

The program is printing "Bin A:
DVD - The Best of (The Beatles),[SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]

Bin B:
Cassette - The Later Years (Michael Jackson),[SKU 1234-3: 1000]"

-It suppose to print 3 song for Bin A but my program is only printing 1 song and the ID of 2 of the other song. May i get a lead on to where is the error? Thanks

Something like this
"Bin A:
CD - The Later Years (Shania Twain), SKU 1234-0: 500
Cassette - Greatest Hits Volume 2 (The Beatles), SKU 1234-1: 25
Cassette - Greatest Hits Volume 1 (Shania Twain), SKU 1234-2: 7720
Bin B:
Cassette - Greatest Hits Volume 2 (Michael Jackson), SKU 1234-3: 1000"

**Norm** · March 16th, 2013, 08:29 PM

Try debugging the code by adding printlns that print out the contents of the collections and variables so you can see what the computer sees when it executes the program.

suppose to print 3 song for Bin A but my program is only printing 1

Print the contents of Bin A every time a song is added to it to follow how many songs Bin A holds.

Where is the loop that goes through the contents of each Bin? Add some printlns to track the looping.

**maple1100** · March 16th, 2013, 08:38 PM

I tested it and the catalog.get() is working fine but it seem the warehouse arraylist only have the size of 2 for some reason. Could you check in the Bin class if I wrote the methods to add to ArrayList and setting it to a get method correctly? Thanks

   public void add(BinItem b)
    {
          myContents.add(b);
    }
 
        public ArrayList<BinItem> getContents()
    {
        return myContents;
    }

**Norm** · March 16th, 2013, 08:44 PM

check in the Bin class if I wrote the methods to add to ArrayList and setting it to a get method correctly

You can do that by adding some calls to the println() method to print out the contents of the ArrayList every time something is added to it. For example, Add this to the add() method and the getContents:

System.out.println("add() mC= "+ myContents);
System.out.println("getContents() mC= "+ myContents);

**maple1100** · March 16th, 2013, 09:20 PM

Sorry to keep bothering you ,Norm. But after modifying my code with what I know, I still can't get it to print 3 song for Bin A instead of 1 song. May I get some more hints? Thanks

The direction I got for this part of the code was
"Use a for-each loop to cycle through all the bins in the warehouse.

● For each bin, extend s by the String "Bin " followed by the name of
the bin, followed by a colon and \n (to start a new line).

● Cycle through all the bin items in the current bin, for each one
extending s by a new line of text that begins with the result of looking
up the current bin item’s SKU in the input catalog, and continues with
a comma followed by the String representation of the bin item."

**Norm** · March 16th, 2013, 09:26 PM

can't get it to print 3 song for Bin A instead of 1 song.

Continue debugging the code by adding more printlns. If you print out the contents of the arraylists every time you add something to the arraylist, what is printed out will show you what is in the arraylist. If there is only one item in the list every time something is added, you need to find out what happened to what was added the last time add() was called. Perhaps the code is creating a new arraylist every time so that what was added the last time is lost when the new arraylist was created.

Where is the loop that goes through the contents of each Bin? Add some printlns to track the looping.

Copy what is printed out by these printlns and paste it here.

I'm done for tonight. Back tomorrow.

**maple1100** · March 17th, 2013, 06:49 AM

Thanks for the help yesterday, Norm. I managed to change the code to print out 3 different song for Bin A but it is using the first song from Bin A for Bin B instead of another random song. I believe this is cause by the loop only getting 3 songs because of the index.

        String s = "";
 
        for (Bin b : warehouse) 
        {   s += "Bin "+b.getName()+"\n";
            for(int i = 0  ; i < b.getContents().size()+1;i++)
            {
                s += b.catalog.get(i).toString()+"\n";
            }
            s+= "\n";
                }
        return s;

This is what it printing
"Bin A
DVD - The Later Years (Eminem)
DVD - Greatest Hits volume 1 (Shania Twain)
Cassette - Love Songs (Michael Jackson)

Bin B
DVD - The Later Years (Eminem)

**Norm** · March 17th, 2013, 06:53 AM

What is printed out by the println statements you are using for debugging? Call println every time something is added to Bin A and Bin B to see what is placed in each bin.

**maple1100** · March 17th, 2013, 07:36 AM

"add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-3: 1000]
add() mC= [SKU 1234-3: 1000]
add() mC= [SKU 1234-3: 1000]
"

String s = "";
 
        for (Bin b : warehouse) 
        {   s += "Bin "+b.getName()+"\n";
            for(int i = 0  ; i <  b.getContents().size();i++)
            {
                s += catalog.get(i).toString()+","+ b.getContents().get(i)+"\n";
            }
            s+= "\n";
                }
        return s;

**Norm** · March 17th, 2013, 07:42 AM

add() mC= [SKU 1234-3: 1000]
add() mC= [SKU 1234-3: 1000]
add() mC= [SKU 1234-3: 1000]

That looks like the same thing is being added to the llist three times. Is that correct? Which Bin is it being added to?

add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]

This print out shows the list as always having 3 items in it? How can that be? I'd expect to see the list with one item and then with two items when a second item is added and then with three items when the next item is added.
The printout does not make sense.

**maple1100** · March 17th, 2013, 07:54 AM

Sorry. I mess up with putting the println you gave me earlier in the wrong method. Here is the correct one.
"add() mC= []
add() mC= [SKU 1234-0: 500]
add() mC= [SKU 1234-0: 500, SKU 1234-1: 25]
add() mC= []
getContents() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
getContents() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
getContents() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
getContents() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
getContents() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
getContents() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
getContents() mC= [SKU 1234-0: 500, SKU 1234-1: 25, SKU 1234-2: 7720]
getContents() mC= [SKU 1234-3: 1000]
getContents() mC= [SKU 1234-3: 1000]
getContents() mC= [SKU 1234-3: 1000]
"

     public ArrayList<BinItem> getContents()
    {System.out.println("getContents() mC= "+ myContents);
        return myContents;
 
    }
 
        public void add(BinItem b)
    {System.out.println("add() mC= "+ myContents);
          myContents.add(b);
    }

**Norm** · March 17th, 2013, 08:10 AM

The printout should show what is in the list AFTER the item is added.
The printouts show that three items were added to one bin and one item was added to the other.
Then the getContents() method was called 7 times for one bin and 3 times for the other bin.
Why are there so many calls to the getContents() method? The call to getContents() should be moved out of the inner loop so it is only called one time in the outer loop.

The printouts show there are 3 items in one bin and one item in the other bin.

So the data is there.

Now you need to look at why the code doesn't get the correct number of items from each bin.

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