Piet Souris wrote:If every line starts with "Gain:" then this will not work, since every key of your Map would be the same. What about the already suggested Map<String, List<Integer>>? That would work, but there would be only one key ("Gain") so you might just as well make a List<Integer>.
But why do you insist on creating a Map? What's wrong with creating a class "Activity" and make a List of these?
Campbell Ritchie wrote:You can probably find a data structure for what you want, but please start by explaining exactly what you want your records to look like.
Don't try arrays, though.
Campbell Ritchie wrote:Please explain more. Are all the lines in the form “Gain:3:Loss:4:Processed:2:Sent:1:”?
Are you using “Gain” as the “K”? In which case you might overwrite the “V”s and your Map might only contain a mapping for the last line.
Don't declare Streams if you can possibly help it. Once you have used a Stream, it is not possible to go back to it, so it is very unusual to write Stream<XYZ> stream = ...;
What you have in line 13 might be a Stream<String> but in line 14 you are turning it into a Stream<String>, so the type will be wrong and line 13 won't compile. You will have to declare it as type Map<...>
Use an IDE to write your code; if you hover your mouse over the method names, you will see a popup telling you the exact return type of each method. Not Stream<T> or anything vague, but Stream<String>.
Let's see what you have: In line 13 you are creating a Stream<String>, but you have some duplicated code. Don't write Paths.get(...) because you have already executed the selfsame code in line 9. Write filePath.
Line 14 changes the Steam to a Stream<String> by correct use of the split() method. If you look here (Java™ Tutorials), you will find that “:” isn't a metacharacter.
You were right to start line 16 with .collect(), but that needs an argument. It is usual to pass a Collector reference; the easiest way to get such a reference being this. Note that will give you a Map<K, List<V>>. I don't know whether that is going to help in you current situation, but at least it will include every line.
Adding discussion to our Streams forrum.