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Tag: collections

Create a list with only base class elements

In Java I have a class and subclass Now let’s say I have List<Bar> bars. How can I create from this a List of Foo (and I only want the a field to appear, not b) Answer What you want is impossible; let’s say you have your bars list which contains 5 Bar instances. It is not possible in java

How to collect data to List from Map using java Stream API?

I have map Map<Nominal, Integer> with objects and their counts: And I need to get such a List<Nominal> from it: How can I do this using the Stream API? Answer We can use Collections::nCopies to achieve the desired result: Ideone demo Remark In the demo, I changed the key-type of the Map from Nominal to Object since the definition of

Comparing the contents of two Treemaps

I have two TreeMaps that I want to compare. I currently have it written down like below but I feel like this could be written more efficiently. I tried looking in to comparators, but I don’t think that’s something I can use for my use-case. The maps are Treemaps because the key must be case-insensitive. Thanks in advance Answer If