HashTable.java

class HashTable {
	   
    class Entry {
        //private final String key; Deleting the Entry  ?
        private String key;
        private String value;
        private Entry next;
        Entry (String key,String value) {
            this.key = key;
            this.value = value;
            this.next = null;
        }
    }

    private Entry tableInstance[];
    private static final int SIZE = 100;

    HashTable () {
        tableInstance = new Entry[SIZE];
    }

    private int getHash (String key) {
        int hash_value = 31;
        for (int i=0;i < key.length();i++) {
           hash_value  += 13 * key.charAt(i) ;
        }
        return hash_value % SIZE;
    }

    public void put(String key,String value) {
        int hVal = getHash(key);
        boolean isKeyFound = false;
        if (tableInstance[hVal] == null) {
            tableInstance[hVal] = new Entry(key,value);
        } else {
            Entry e = tableInstance[hVal];
            while (e.next != null) {
                if (e.key == key) {
                    e.value = value;
                    isKeyFound = true;
                    break;
                }
                e = e.next;
            }
            if (false == isKeyFound) {
            	Entry head = tableInstance[hVal];
                Entry newHead = new Entry(key,value); 
                newHead.next = head;
                head = newHead;
            }
        }
    }

    public String get(String key) {
        int hVal = getHash(key);
        Entry e = tableInstance[hVal];
        while (e.next != null) {
            if (e.key == key) {
                return e.value;
            }
            e = e.next;
        }
        return null;
    }

    public bool delete(String key) {
        int hVal = getHash(key);
        Entry e = tableInstance[hVal];
        if (e.next == null) {
            e = null;
            return true;
        }
        while (e.next != null) {
            if (e.key == key) {
                e.key = e.next.key;
                e.value = e.next.value;
                e = e.next.next;
                return true;
            }
        }
        return false;
    }

}