Updating a hashmap Free live small tists chat
Submit a bug or feature For further API reference and developer documentation, see Java SE Documentation.
That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Or we could combine the old value and the new value. If we insert a key and a value into a hash map, and then insert that same key with a different value, the value associated with that key will be replaced.
Even though the code in Listing 8-24 calls that represents a value that might or might not exist.
There are several other facts to bear in mind: If concurrent updates are under strict control, aggregate status would still be reliable.
, which determines how it places these keys and values into memory.
The values that the references point to must be valid for at least as long as the hash map is valid.
We’ll talk more about these issues in the “Validating References with Lifetimes” section in Chapter 10.
We can get a value out of the hash map by providing its key to the Although the number of keys and values is growable, each key can only have one value associated with it at a time.
When we want to change the data in a hash map, we have to decide how to handle the case when a key already has a value assigned.