How is HashTable.java done?

HashTable

Implement the map interface methods in the HashTable class. Each element in the hash table should be maintained by an instance of a ListNode which provides fields for the key-value pair associated with a hash table element and a reference for any potential next element that may follow a given hash table element in one of the lists. The constructor for the class takes the number of buckets in the linked-list as a parameter. Ratio of the number of buckets in the linked-list to the number of elements stored in the entire hash table is a key heavily influences the efficiency of map operations in the hash table. Recall that a hash table is an array of linked-lists and the hash function is used to compute the index of the linked-list in the array where a key must be stored. When searching or inserting, hash the key using the hash function to compute the index of the bucket in which the key-value pair should be stored. Also recall that the key must be unique which means that upon insert and once the bucket is identified through hashing, perform a search on the key in the associated linked-list to determine whether the key is already stored in the linked-list before performing any insertion. This means it cannot arbitrarily perform tail insertions on the linked-list, so there is no benefit of storing a tail pointer because it will end up searching for the tail anyway. For the sake of profiling comparisons, only count the comparisons when searching the linked-list itself.

/* TODO - Summarize this class */ public class HashTable implements Map {    // TODO - Document all instance variables   private final ListNode[] buckets;    public HashTable(int length) {     this.buckets = new ListNode[length];   }    /// TODO - Document this method   public void insert(String key, String value, int[] profile) {     // TODO: write this method   }    /// TODO - Document this method   public String search(String key, int[] profile) {     // TODO: write this method     return null;   }    /// TODO - Document this method   public void clear() {     // TODO: write this method    }    /// The number of buckets in the hash table   /// @return the number of buckets in the hash table   public int length() {     return buckets.length;   }   /// Hashing function converts a string of characters into an index   /// bounded by the size of the hash table's array   /// @param key input to hash   /// @return bucket index corresponding to the hashed key   private int hash(String key) {     return Math.abs(key.hashCode() % buckets.length);   } } 

Other useful files to go with it:

public interface Map {   public void insert(String key, String value, int[] profile);   public String search(String key, int[] profile);   public void clear(); } 

public class ListNode {    private final KVP data; // The key value pair associated with this node   public ListNode next;  // Reference to any child node    /// Parameterized constructor forces users of the class to provide both   /// key and value on creation.   /// @param key the unique identifier for this node. immutable   /// @param value the value associated with the provided key   public ListNode(String key, String value) {     data = new KVP(key, value);     next = null;   }    /// Accessor to retrieve the key from the key-value pair   /// @return the unique key stored in this node   public String getKey() {     return data.key;   }    /// Accessor to retrieve the value from the key-value pair   /// @return the value stored in this node   public String getValue() {     return data.asString();   } }