Hashmap adding

Question

for exemple:
i have a hashmap donations. that stores the name of the donator and the amount:
donations.put("bob";150);
donations.put("sarah";100);
System.out.println("bob");
150 will return.
if i were to add:
donations.put("bob";100);
that it will keep adding money to the total amount that bob donated right?

Answer 1

you have to do it like this
if (donations.containsKey("bob"))
donations.put("bob", donations.get("bob") + 100);
else
donations.put("bob", 100);
and your syntax for adding key/value is wrong
they should be separated by comma
also for getting the value you need to do it like this
System.out.println(donations.get("bob")); //returns the value

Answer 2

Well...
If you use the same key to define a new value in Hashmap it will override the old value of that key.
So for your example, you should do the following:
int oldValue = donations.get("bob");
donations.put("bob", oldValue+100/*value to add*/);
I suggest you to write a method to do this:
public void addMoneyToPerson(String person, int value){
donations.put(person,
donations.get(person)+ value);
//more compact version
}