Populate a list of object from a map using stream

Question

I have the below map of and a string

/** 4->"welcome" 3->"to" 2->"my" 1->"blog" */ Map<Integer, String> myMap = ImmutableMap.of(4, "welcome", 3, "to", 2, "my",1,"blog"); String s= "welcome to my blog everyone"

Now I need to poulate the below object list by deleting the words from the string based on the order in decending order(the map is already sorted decending)

{ "level": 1, "delete":["welcome"], "modString":"to my blog everyone" } { "level": 2, "delete":["welcome","to"], "modString":"my blog everyone" } { "level": 3, "delete":["welcome","to","my"], "modString":"blog everyone" } { "level": 4, "delete":["welcome","to","my","blog"], "modString":"everyone" }

The list has the type Delete

public class Delete { private Integer level; private String modString; private List<String> delete; public Delete( Integer level, String modString, List<String> delete) { this.level = level; this.modString = modString; this.delete = delete; } //getters and setters } }

I can do it by iterating the map but I was thinking if this can be done using Streams.

Have you looked at stackoverflow.com/questions/35486826/…? — jordan
– jordan, Commented Nov 26, 2019 at 14:22

raven · Accepted Answer · 2019-11-26 14:54:39Z

I don't quite get the purpose of the map's keys and their relation to level. But I assume you want a solution to java's variables inside lambdas having to be final. For that purpose you can use java.util.concurrent.atomic.AtomicReference or other classes in the same package.

final AtomicReference<String> modString = new AtomicReference<>(s); final Comparator<Map.Entry<Integer, String>> comparing = Comparator.comparing(Map.Entry::getKey); final List<String> deletedOnes = new ArrayList<>(myMap.size()); final List<Delete> result = myMap.entrySet().stream().sorted(comparing.reversed()).map(entry -> { deletedOnes.add(entry.getValue()); modString.set(modString.get().replaceFirst(entry.getValue(), "").trim()); return new Delete(myMap.size() - entry.getKey() + 1, modString.get(), new ArrayList<>(deletedOnes)); }).collect(Collectors.toList());

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