Complete Implementation of Hash Tables

import java.util.ArrayList;
// Class to represent entire hash table
class HashTable
{
	// to store chains of slots 
	private ArrayList<HashEntry> bucket;
	// num of slots in each bucket
	private int slots;
	// total hashed keys
	private int size;
	public HashTable()
	{
		bucket = new ArrayList <HashEntry>();
		slots = 5;
		size = 0;
		//Initialize nodes
		for (int i = 0; i < slots; i++)
			bucket.add(null);
	}
	public int size() { return size; }
	public boolean isEmpty() { return size() == 0; }
  //Look for the index based on key
  // search function
  private int getIndex(String key)
	{
		int hashCode = key.hashCode();
		int index = hashCode % slots;
		return index;
	}
  //delete a value
	public int delete(String key)
	{
    
    //Look for the index based on key		
    int b_Index = getIndex(key);
		HashEntry head = bucket.get(b_Index);
		// Search the key in slots
		HashEntry prev = null;
		while (head != null)
		{
			// If the key exists
			if (head.key.equals(key))
				break;
			//If the key not found yet
			prev = head;
			head = head.next;
		}
		// If the key does not exist
		if (head == null)
			return 0;
		size--;
	 // Delete the value by  key
		if (prev != null)
			prev.next = head.next;
		else
			bucket.set(b_Index, head.next);
		return head.value;
	}
  //to get a value for key from table
  public int get(String key)
	{
		int b_Index = getIndex(key);
		HashEntry head = bucket.get(b_Index);
		// Find the key in slots
		while (head != null)
		{
			if (head.key.equals(key))
				return head.value;
			head = head.next;
		}
		// If key does not exist
		return 0;
	}
	// Insert the key into table
	public void insert(String key, int value)
	{	
		int b_Index = getIndex(key);
		HashEntry head = bucket.get(b_Index);
		// See if the key exists
		while (head != null)
		{
			if (head.key.equals(key))
			{
				head.value = value;
				return;
			}
			head = head.next;
		}
		// Insert key into the bucket 
		size++;
		head = bucket.get(b_Index);
		HashEntry new_slot = new HashEntry(key, value);
		new_slot.next = head;
		bucket.set(b_Index, new_slot);
		//If 60% of the array gets filled, double the size
		if ((1.0*size)/slots >= 0.6)
		{
			ArrayList <HashEntry> temp = bucket;
			bucket = new ArrayList<>();
			slots = 2 * slots;
			size = 0;
			for (int i = 0; i < slots; i++)
				bucket.add(null);
			for (HashEntry head_Node : temp)
			{
				while (head_Node != null)
				{
					insert(head_Node.key, head_Node.value);
					head_Node = head_Node.next;
				}
			}
		}
	}
}