So I am creating a Hash Table that uses an Array of Linked Lists of Arrays. Let me take a second to explain why this is.
So I have previously implemented Hash Tables by creating an Array, and each element of the array is a Linked List. This way I could quickly look up a LL of 450,000 elements by searching for the hash value first in the array, and searching the elements of this LL. I should add that this is a project for school and I cannot just use the Hash Tables that comes with java.
Now I want to do something similar... but I massive have a LL of Arrays that I need to search. Here each element of the LL is line of a text file, which represented by a 4 element array, where each of the 4 elements is a different string that was tab delimited in the input file. I need to be able to quickly access the 2nd, 3rd, and 4th string that was located in each line, and that is now an element of this array.
So What I want is to be able to create an Array of LL of Arrays... first I will find the sum of the ascii values of the second element of an array. Then I will hash the entire array using this value into by Hash Table. Then when I later need to find this element, I will go to the corresponding element of the array, where I have a list of arrays. I will the search for the 2nd value of each array in the list. If i find the one I want, then I return that array, and use the 3rd and 4th element of this array.
As I said, I have this working fine for an Array of LL, but adding the extra dimension of Arrays inside has thrown me off completely. I think it is mostly just figuring out syntax, since I have successfully initialized a Array of LL of Arrays (public static LinkedList[] RdHashLL) so it appears that Java is okay with this in principal. However, I have no idea how to put elements into the Hash Table, and how to read them out.
Below is my code for a ARRAY OF LINKED LISTS that works FINE. I just need help getting it to work for an ARRAY OF LL OF ARRAYS!
public class TableOfHash{
public static LinkedList<String>[] HashLL;
//HASH FUNCTION - Finds sum of ascii values for string
public static int charSum(String s){
int hashVal = 0;
int size = 1019; //Prime Number around size of 8 char of 'z', (8 chars is amoung largest consistantly in dictionary)
for(int i = 0; i < s.length(); i++){
hashVal += s.charAt(i);
}
return hashVal % size;
}
//CREATE EMPTY HASH TABLE - Creates an array of LL
public static void makeHash(){
HashLL = new LinkedList[1019];
for(int i=0; i<HashLL.length; i++){
HashLL[i] = new LinkedList<String>();
}
}
//HASH VALUES INTO TABLE!
public static void dictionary2Hash(LinkedList<String> Dict){
for(String s : Dict){
HashLL[charSum(s)].add(s);
//Finds sum of char vales of dictionary element i,
//and then word at i to the HashLL at point defined
//by the char sum.
}
//Print out part of Hash Table (for testing! for SCIENCE!)
//System.out.println("HASH TABLE::");
//printHashTab();
}
//SEARCH HashTable for input word, return true if found
public boolean isWord(String s){
if(HashLL[charSum(s)].contains(s)){
wordsfound++;
return true;
}
return false;
}
}
I have made some attempts to change this, but for things like if(HashLL[charSum(s)].contains(s)) which searches the LL at the element returned by charsum(s)... I have no idea how to get it to work when it is a LL of Arrays and not of Strings. I have tired HashLL[charSum(s)].[1].contains(s)), and HashLL[charSum(s)][1].contains(s)), and various other things.
The fact that a Google search for "Array of Linked Lists of Arrays" (with quotes) turns up empty has not helped.
Last bit. I realize there might be another data structure that would do what I want, but unless you believe that a Array of LL of Arrays is a totally hopeless cause, I'd like to get it to work as is.
LinkedList<String[]>[] hashLL;?