learning java stream, how to pass a value from the outer loop to the nested loop in a functional way - java-8

Question

I have map of a map of strings. This map is a parsing of a json object and represents the criteria entered by the user to filter a list in the UI.
In the rest service I want to populate an object with data comes from this map. Unfortunately I cannot change queryModel Object. Query Model object has a list of filters. Each filter has a list of fields and a list of operations to be applied to the field. My goal is to convert the following code with java 8 stream.
for(Map.Entry<String,Map<String,String>> entry: filters.entrySet()) {
Filter filter = new Filter();
filter.setFields(new ArrayList<String>());
filter.getFields().add(entry.getKey());
filter.setValues(new ArrayList<String>());
filter.setOperators(new ArrayList<String>());
if (entry.getValue() != null) {
for(String key : entry.getValue().keySet()) {
if(key.equals("value")) {
filter.getValues().add(entry.getValue().get(key));
}
else if(key.equals("matchMode")){
filter.getOperators().add(entry.getValue().get(key));
}
}
queryModel.getFilters().add(filter);
}
As you can see I first set the name of the field in the fields list and then for that field I loop in the values to get the value entered and the match mode. In a functional I don't know ho to save the field of the outer loop to set it in the filter object created in the inner loop.
That was my attempt
public static Filter getFilter(Map.Entry<String,String> entry) {
Filter filter = new Filter();
filter.setFields(new ArrayList<String>());
filter.getFields().add(entry.getKey());
filter.setValues(new ArrayList<String>());
filter.setOperators(new ArrayList<String>());
if(entry.getKey().equals("value")) {
filter.getValues().add(entry.getValue());
}
else if(entry.getKey().equals("matchMode")){
filter.getOperators().add(entry.getValue());
}
return filter;
}
List<Filter> filterList = filters.entrySet().stream()
.filter( stringMapEntry -> stringMapEntry.getValue() != null)
.flatMap( entry -> entry.getValue().entrySet().stream())
.map (innerEntry-> QueryModelAdapter.getFilter(innerEntry))
.collect (Collectors.toList());
queryModel.setFilters (filterList);
I need in QueryModelAdapter.getFilter the entry of the flat map. How can I do that?

Answer 1

Before I say anything, be polite when asking questions. Nobody gets paid for answering questions here. All are doing it for their pleasure.
So, be nice to them at least with your words.
Alright, I think your question is more suitable for CodeReview than StackOverflow.
One thing to note, You can't rewrite your legacy java projects to have every single line with lambdas and streams.
Sometimes, it's better the old fashioned way than the new features.
You don't need to iterate a Map to retrieve its matching value. You can remove that Inner-loop.
Let's take your current class (whatever the class you copied the code from) named it as RespectOthers.java
private static Filter getEmptyFilter(){
Filter filter = new Filter();
filter.setFields(new ArrayList<String>());
filter.setValues(new ArrayList<String>());
filter.setOperators(new ArrayList<String>());
return filter;
}
private static Filter setKeyAndValues(Filter inputFilterObj, Map.Entry<String,Map<String,String>> entry, QueryModel queryModel){
inputFilterObj.setFields(new ArrayList<String>());
inputFilterObj.getFields().add(entry.getKey());
if (entry.getValue() != null) {
inputFilterObj.getValues().add(entry.getValue().get("value"));
inputFilterObj.getOperators().add(entry.getValue().get("matchMode"));
queryModel.getFilters().add(inputFilterObj);
}
return inputFilterObj;
}
List<Filter> finalOutput = filters.entrySet().stream()
.map(e -> RespectOthers.setKeyAndValues(RespectOthers.getEmptyFilter(), e, myQueryModel))
.collect(Collectors.toList());