Printing Values From a HashMap Java


Printing Values From a HashMap Java



I have a Java program that I am currently making, and am stuck with printing out the keys and the values associated with each key of my hashMap.



This is the HashMap that I have declared currently:


HashMap<String, ArrayList<String>> mp = new HashMap<>();



Basically assuming that I have the following code written out


mp.put(key1, list.add(value1));
mp.put(key1, list.add(value2));
mp.put(key1, list.add(value3));

mp.put(key2, list.add(value5));
mp.put(key2, list.add(value4));

mp.put(key3, list.add(value6));



I want to print the map out like this:



Is there any way I can get that done? Thanks for all the help I can get. Please let me know if any more clarification is needed.





mp.computeIfAbsent(key1, k -> new ArrayList<>()).add(value1);
– shmosel
Jun 29 at 21:38


mp.computeIfAbsent(key1, k -> new ArrayList<>()).add(value1);





I am not sure if this is correct or if it will work as I have not tested it yet:: then why are you asking? Test your code and do experiments first. And read the javadoc.
– JB Nizet
Jun 29 at 21:38






I tested it, and @shmosel this is not a duplicate, the other post is adding to a list within a hashmap. I know how to do that. I am asking how do I print to console the full hashmap.
– Andy Chan
Jul 1 at 1:51






You should update your code example so it compiles (and builds a real example map). I think it was misleading people. It looked like you were asking how to fill the map as part of your question. I tried to clarify the question a little bit, but you should still fix the code example.
– Radiodef
Jul 1 at 2:35






mp.forEach((k, v) -> System.out.println(k + ": " + String.join(", ", v)));
– shmosel
Jul 1 at 4:19



mp.forEach((k, v) -> System.out.println(k + ": " + String.join(", ", v)));









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