Why is .filter not removing null values from my Map<String,Object>

PremiumAluminium :

I'm trying to filter out unnecessary null values from my LinkedHashMap. However it isn't actually removing these values.

Variable declaration

Map<String,Object> dataDictionary = new LinkedHashMap<>();

Small section of what is being returned when i sysout.print(dataDictionary) after using the filter method.

[industryCodes=<null>,regionCodes=<null>,andKeywords=false,id= 
<null>,resultsPerPage=20,keywords=<null>,omitKeywords=<null>}

Java code

dataDictionary= dataDictionary.entrySet()
            .stream()
            .filter(entry -> entry.getValue()!=null)
            .collect(Collectors.toMap(Map.Entry::getKey,
                            Map.Entry::getValue));

Expecting the null values and their keys to be removed but this doesn't seem to be happening.

Amongalen :

What you're doing is totally unnecessary. The following is enough to remove all null values:

dataDictionary.values().removeIf(Objects::isNull);

No need for streams and such.

Edit: Here is the code I've tested it with:

Map<String,Object> dataDictionary = new LinkedHashMap<>();
dataDictionary.put("industryCodes", null);
dataDictionary.put("regionCodes", "test");
dataDictionary.put("omitKeywords", null);
dataDictionary.put("resultsPerPage", 21);
dataDictionary.values().removeIf(Objects::isNull);
System.out.println(dataDictionary);

Output: {regionCodes=test, resultsPerPage=21}

With the removeIf line commented out I get: {industryCodes=null, regionCodes=test, omitKeywords=null, resultsPerPage=21}

Seems to be working for me.

Maybe there is something wrong with your values and they actually aren't null?

Edit2: As suggested by Holger, before Java 8 you can use the following:

dataDictionary.values().removeAll(Collections.singleton(null));