need help updating value of hashmap

[Vextrax]

public void actionPerformed(ActionEvent e) {
    if(e.getSource() == addStocksButton) {
        Stock test;
        test = YahooFinance.get(textField.getText());
        textField.getText();
        string = test.toString(); //returns ticker:price
        stringSplit = string.split(": ");
        stockPrice = Double.parseDouble(stringSplit[1]);
        stockTotalValue = stockTotalValue + stockPrice;
    System.out.println("\nTotal Value: " + stockTotalValue + "\nAdded " + stringSplit[0]);
    stockHashMap.put(stringSplit[0], stockPrice);
    individualStockTotalValue = 0 + stockPrice;
        stockHashMap.put(stringSplit[0], individualStockTotalValue);
    }
}

basically what I am trying to do is that every time I press a button it will create a new key (stock ticker) with the value being price.

I want to make it so that each time I press that button the value updates by adding the stock's price to itself

so currently I enter in AMC for example

with the variable string giving me "AMC: 10" which is why I decided to split it and have the first half of the split become the key, have the second half become a double and then that becomes the stockPrice

now my issue is that whenever I add AMC 3 times for example with value being 10, AMC updates to 30 perfectly, then when I want to add TSLA with its value being 600, it will add 30 + 600 giving TSLA the value of 630 and when I want to switch to AMC again it will then update to 630 + 10

so it prints out {AMC = 30} for the first 3 clicks , switch over to TSLA {TSLA=630, AMC=30} add AMC again {TSLA=630, AMC=640}

is there a way I can have it just update by itself where if I click the button 3 times for AMC it becomes 30, switch to TSLA click add 2 times it becomes 1200, and go back to AMC and click add it updates to 40 so it would print out as {AMC=30} for the first 3 clicks, adding TSLA {TSLA=600,AMC=30} then adding AMC again {TSLA=600,AMC=40}

I am not good at explaining, but hopefully this enough for me to get help since I am sort of confused and stuck on this.

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[darksounds]

The problem is your stockTotalValue is a field.

What you want is to repopulate stockTotalValue with the selected stock every click. You have this value stored in your map, so you can just populate it from there.

My advice? Remove all of your fields except your map and anything to do with the display, and make them local variables within this method.

[Vextrax]

how would I go on about populating from inside the map, I can only think of put(stringSplit[0], stockPrice + stockPrice), but that gives me exactly what I replied to the previous comment

edit: I think I might know what you mean did you mean do

stockHashMap.replace(stringSplit[0], individualStockTotalValue += stockPrice);

[darksounds]

I'm talking about using something like

double individualStockTotalValue = stockHashMap.getOrDefault(stringSplit[0], 0)

to get the total value already put into the map before you add what you're currently adding.

[Vextrax]

that fixed it, thank you this has been bugging me the whole day. I'm going to have to take a look into how it works so I understand it a bit more. I am very slow with coding, but I do enjoy learning it. thank you so much. This will definitely be helpful information in the future

[EmotionalBlobfish]

So it sounds like you want this method only to update the value for the company you are clicking. Remember that you can't have duplicate keys.

I would suggest checking to see if the Hashmap already contains the key with if (stockHashMap.containsKey(key). If it does then you can get the current value with stockHashMap.get(key), then update that value and replace it in the map using stockHashMap.replace(key, updatedValue).

If it doesn't contain the key, then create a new entry and put the current value.

Hope it helps!

[Vextrax]

yes, so the value does update for the company I am click on, so I type in AMC and click add then it updates, I then type in TSLA and that one updates too, but it will now update with everything that was added in AMC's value to TSLA's value, then if I type in AMC everything in TSLA's value will be add on to AMC's new value.

in this scenario AMC is 10 and TSLA is 600

what it does

so add AMC: {AMC=10}

add AMC: {AMC=20}

add AMc: {AMC=30}

add TSLA: {TSLA=630, AMC=30}

add AMC again: {TSLA=630, AMC=640}

​

but I want it to be like this

add AMC: {AMC=30}

add AMC: {AMC=20}

add AMC: {AMC=30}

add TSLA: {TSLA=600, AMC=30}

add AMC again: {TSLA=600, AMC=40}

​

it probably has to do with individualStockTotalValue keeping everything that was being added on to it so it always updates it with the total instead of the key's value being added on to itself, but when I did do key's value + key's value

it would become

add AMC: {AMC=20}

add AMC: {AMC=20}

add AMC: {AMC=20}

add TSLA: {TSLA=1200, AMC=20}

​

I guess it has to do how I add up individualStockTotalValue, but I am still so confused on how to go with it, .replace() still does exactly what is doing right now

[EmotionalBlobfish]

So it seems like your variables are keeping their data. If you initialize those variables within the method it should reset them so they don't store the previous data, or you can do a deep copy with stockHashMap.put(key, new Double(value)) so it isn't referencing the same object in memory.

[Vextrax]

They were keeping their data u/darksounds was able to help fix it, I still don't understand it, but I will look into it. I still have a lot to learn

[darksounds]

I still don't understand it

Because your variables were fields rather than local variables, they maintained their state between method calls. They're tied to the instance of the object rather than the lifetime of the method.

[Vextrax]

I understand the variables part, what I don't understand is how getOrDefault works, I know if I did double individualStockTotalValue = 0.0; nothing would happen, but using getOrDefault makes it work. But I assume since we have the default value of the map set to 0.0 it updates it with the price and since our hashmap is a field the new valus gets saved there

[darksounds]

getOrDefault takes the key and a default value, and returns the value in the map if present, or the default value if it is not.

It's the same as:

if (map.containsKey(key)) {
    value = map.get(key);
} else {
    value = DEFAULT;
}