I know how to convert List<Object> into Map<String,String> as you can see in this code:
Map<Long, String> divMap = divs.stream() .collect(Collectors.toMap(Div::getId, Div::getName)); The output of this is:
"1": "A", "2": "B"
But I want to return List<Map<String,String>> with the output given below:
["id":"1",Name="A"] ["id":"2",Name="B"]
The easiest way would be to help yourself by writing a separate toMap helper method that converts a Div into a Map<String, String>.
private Map<String, String> toMap(Div div) { Map<String, String> result = new HashMap<>(); result.put("id", div.getId().toString()); result.put("name", div.getName()); return result; } ...and everything becomes much easier then:
List<Map<String, String>> divMap = divs.stream() .map(this::toMap) .collect(Collectors.toList()); Also, it looks like you are trying to reinvent a wheel. Consider using some serialization/deserialization libraries.
You can use Stream's reduce method, like:
final List<Div> divs = Arrays.asList( new Div("1", "A"), new Div("2", "B") ); final List<Map<String, String>> result = divs.stream() .reduce(new ArrayList<>(), (list, div) -> { list.add(new HashMap<String, String>() {{ put("id", div.getId()); put("name", div.getName()); }}); return list; }, (a, b) -> a); Reduce method expects 3 parameters:
BiFunction that provides 2 parameters: accumulator (type List<Map<String,String>> in your case) and current value taken from stream iteration (Div object) and returns a value of accumulator type(a,b) -> a is enough.This approach pretty similar to folding known from functional programming.
reduce is an overkill, check my answer :)