summing value within Hashtable

[dc0m]

Hello,

I'm having problem trying to figure out how to use Hashtable data structure. I'm reading names and number of occurrences for that name from text files. I'm using name as key and number of occurrences as value. If the name exist in Hashtable I want to sum the two values and store it back in Hashtable. How do I do that? Here is where I'm at (Bear in mind I'm very new to programming):

public class HashTableImplementation {
	
	double sum = 0;
	Hashtable hashList = new Hashtable();

	public HashTableImplementation()
	{
		hashList = new Hashtable();

	}
	
	public void addToHasTable(String name, double weight)
	{
		if (!hashList.containsKey(name))
			hashList.put(name, weight);
		else 
		{
			//sum weights for that name
                }
	}

Any help would be appreciated.

[Norm]

I want to sum the two values and store it back in Hashtable

If the key does not exist, create a new object with the data and put it in the hashtable.
If the key is there, get the value, add the new value to the existing one and put that object back.
You are using the autoboxing feature of the compiler to put your values in the hashtable. The put method takes two objects. It does NOT take a primitive like a double. The compiler is wrapping your double into a Double.

[dc0m]

Thanks for fast response.

I managed to do that, by doing this.

sum = weight + Double.parseDouble(hashList.get(name).toString());
hashList.put(name, sum);

But this just adds another Hashtable entry it does not add values to the same entry =/

Let's say I have Mary, 33, and then I get another Mary with 40. I want to add to "Mary" (which has value 33) value 40. The result would be one Mary,73. But istead I get two Marys, one with 33 and one with 73. Where am I making mistake?

Thanks again.

[Norm]

I don't know how you can get two keys = Mary.
Can you post the code.

sum = weight + Double.parseDouble(hashList.get(name).toString());

Putting all the code in one statement is a poor way to do it.

[dc0m]

Never mind, that actually worked, there was actually totally different reason why it printed out two Marys.

Thanks a lot friend.

"Putting all the code in one statement is a poor way to do it. "

What is the right way to do it?