How to fill Vaadin Grid with Map items type

问题

I want to fill my Vaadin Grid with Map<String, Object> items. Thats because I get my data from database like this(maybe it's main problem):

List<Map<String, Object>> result = jdbcTemplate.queryForList("select * from db", new Object[]{});

Now lets say that I create my test List and fill it with some maps:

List<Map<String, Object>> items = new ArrayList<>();
items.add(map);
items.add(map2);

I know how to do it with non dynamic data model, for example:

grid.addColumn(Person::getName).setCaption("Name");
grid.addColumn(Person::getAge).setCaption("Age");

But how can I create my Grid columns so it will use my keys from map? What I have by now:

Grid<Map<String, Object>> grid = new Grid<>();

items.get(0).keySet().forEach(key ->
    grid.addColumn(c -> c.get(key)));

grid.setItems(items);

It gives me output:

b2 / b3 / b1

And expected:

a1 / a2 / a3

b1 / b2 / b3

I have no clue how can I get to my item in every single map in list. And also why doesnt it keep an order? Appreciate every answer!

回答1:

Use LinkedHashMap instead of Map.

LinkedHashMap preserves the insertion order.

来源：https://stackoverflow.com/questions/45548691/how-to-fill-vaadin-grid-with-map-items-type