Programming Forums > Application Development > Java

ELHEK · Sep 26th, 2006, 10:44 PM

Hey everyone, im doing an project for uni, and i have to make a dictionary, which is an array of linked list, where each element of the array is a linked list which stores all the words starting with a certain letter of the alphabet.
the words for the dictionary are ment to be read in from a dictionary and then sorted in the array of linked lists. im still new at programming and cant understand how to make an array with each element consisting of a linked list. any help would be great! thx!

Mjordan2nd · Sep 26th, 2006, 10:55 PM

I believe you would create an array of lists just like you would create an Array of anything else.

titaniumdecoy · Sep 26th, 2006, 11:41 PM

I'm not sure what your problem is. However, I would recommend using an ArrayList to store the LinkedList objects because it is much more flexible (you can add and remove elements easily). If you choose to go about your task in this way, you might use code similar to the following:

(Toggle Plain Text)

ArrayList<LinkedList> dict = new ArrayList<LinkedList>();
dict.add(linkedListObject1);
dict.add(linkedListObject2);
// ...

If your question is how to store LinkedList objects in a simple array, remember that all objects in Java are stored as references. Therefore, you can create an array of LinkedList objects easily; you cannot, however, alter the number of elements the array can store once it has been created. (By default, all indices are set to null.) You can do this as follows:

(Toggle Plain Text)

LinkedList[] dict = new LinkedList[NUM_ELEMENTS];
dict[0] = linkedListObject1;
dict[1] = linkedListObject2;
// ...

metsfan · Sep 27th, 2006, 4:19 PM

Creating an array of objects is no different than creating an array of primary data types. Im assuming you know how to make an array of primary data types, but just to refresh your memory:

(Toggle Plain Text)

int[] a = new int[7];  //create the array
a[0] = 0;  // intialize indexes
a[1] = 1;
...

As you probably already know, this creates an array of 7 integers. Creating an array of LinkedList objects is no different.

(Toggle Plain Text)

LinkedList[] dictionary = new LinkedList[26]  //create the array

Now, you must remember all that does is create the pointers in memory. None of these indexes are initialzed. In order to actually use the linked lists, you will have to initialize each one. a for loop does the trick:

(Toggle Plain Text)

for(int i = 0; i < dictionary.length; i++) 
{
dictionary[i] = new LinkedList();
}

Your dictionary is now ready to go!

Now we just use it as we would any linked list:

(Toggle Plain Text)

dictionary[0].add("apple");
dictionary[0].add("amazing");
dictionary[1].add("ball");
...

Sep 26th, 2006, 10:44 PM	#1
ELHEK Newbie Join Date: May 2006 Posts: 9 Rep Power: 0	array of listed lists Hey everyone, im doing an project for uni, and i have to make a dictionary, which is an array of linked list, where each element of the array is a linked list which stores all the words starting with a certain letter of the alphabet. the words for the dictionary are ment to be read in from a dictionary and then sorted in the array of linked lists. im still new at programming and cant understand how to make an array with each element consisting of a linked list. any help would be great! thx!

Sep 26th, 2006, 10:55 PM	#2
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	I believe you would create an array of lists just like you would create an Array of anything else. __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Sep 26th, 2006, 11:41 PM	#3
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	I'm not sure what your problem is. However, I would recommend using an ArrayList to store the LinkedList objects because it is much more flexible (you can add and remove elements easily). If you choose to go about your task in this way, you might use code similar to the following: (Toggle Plain Text) ArrayList<LinkedList> dict = new ArrayList<LinkedList>(); dict.add(linkedListObject1); dict.add(linkedListObject2); // ... ArrayList<LinkedList> dict = new ArrayList<LinkedList>(); dict.add(linkedListObject1); dict.add(linkedListObject2); // ... If your question is how to store LinkedList objects in a simple array, remember that all objects in Java are stored as references. Therefore, you can create an array of LinkedList objects easily; you cannot, however, alter the number of elements the array can store once it has been created. (By default, all indices are set to null.) You can do this as follows: (Toggle Plain Text) LinkedList[] dict = new LinkedList[NUM_ELEMENTS]; dict[0] = linkedListObject1; dict[1] = linkedListObject2; // ... LinkedList[] dict = new LinkedList[NUM_ELEMENTS]; dict[0] = linkedListObject1; dict[1] = linkedListObject2; // ...

Sep 27th, 2006, 4:19 PM	#4
metsfan Programmer Join Date: Dec 2005 Posts: 57 Rep Power: 0	Creating an array of objects is no different than creating an array of primary data types. Im assuming you know how to make an array of primary data types, but just to refresh your memory: (Toggle Plain Text) int[] a = new int[7]; //create the array a[0] = 0; // intialize indexes a[1] = 1; ... int[] a = new int[7]; //create the array a[0] = 0; // intialize indexes a[1] = 1; ... As you probably already know, this creates an array of 7 integers. Creating an array of LinkedList objects is no different. (Toggle Plain Text) LinkedList[] dictionary = new LinkedList[26] //create the array LinkedList[] dictionary = new LinkedList[26] //create the array Now, you must remember all that does is create the pointers in memory. None of these indexes are initialzed. In order to actually use the linked lists, you will have to initialize each one. a for loop does the trick: (Toggle Plain Text) for(int i = 0; i < dictionary.length; i++) { dictionary[i] = new LinkedList(); } for(int i = 0; i < dictionary.length; i++) { dictionary[i] = new LinkedList(); } Your dictionary is now ready to go! Now we just use it as we would any linked list: (Toggle Plain Text) dictionary[0].add("apple"); dictionary[0].add("amazing"); dictionary[1].add("ball"); ... dictionary[0].add("apple"); dictionary[0].add("amazing"); dictionary[1].add("ball"); ...

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Programming Forums > Application Development > Java

array of listed lists