Is there a Java version of the creating an array of dictionaries like in Swift

Question

In Swift I can write a dictionary like this:

let myDict = [
    [
        "title": "some title",
        "val": "some val",
        "url": "some url"
    ],
[
        "title": "some title",
        "val": "some val",
        "url": "some url"
    ],
]

Is there a android Java version of that?

@LeoDabus a simple search, based off how to create a dictionary in java will point them in the right direction, no? If one knows how to create a map, they can surely make a map of maps. :) — cela, Jun 01 '18 at 20:47
This should help you as well https://stackoverflow.com/questions/1493162/how-does-one-instantiate-an-array-of-maps-in-java — cela, Jun 01 '18 at 20:53
Java doesn't have any literal syntax equivalent to Swift's. That's just the first of many pain points your bound for. Sorry :/ — Alexander, Jun 01 '18 at 21:59

Code-Apprentice · Answer 1 · 2020-03-02T19:49:35.350

Java does not have dictionary or array literals. Instead we have interfaces, java.util.Map and java.util.List in the Collections API. These have several implementations including java.util.HashMap and java.util.ArrayList. You can combine these in any way you want. Creating a list of maps can unfortunately become quite verbose since you have to call the appropriate methods to add elements to these data structures. I suggest that you read about the Collections API to learn about all of the data structures that are available in Java.

Maihan Nijat · Answer 2 · 2018-06-01T23:39:17.197

1

Import utility:

import java.util.HashMap;

And then you can use Map. The first line declares an empty variable with the type of HashMap and the two next lines add data into it.

Map vehicles = new HashMap();
vehicles.put("BMW", 5);
vehicles.put("Mercedes", 3);

As @Code-Apprentice mentioned. You need to import the required utility.

edited Jun 01 '18 at 23:39

answered Jun 01 '18 at 20:44

Maihan Nijat

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`You need to import the required utility` You may as well mention what it is, and put the whole import line in for convenient copying. – Alexander Jun 01 '18 at 21:58
@Alexander Thanks for the review. I edited the answer. – Maihan Nijat Jun 01 '18 at 23:39

score 0 · Answer 3 · answered Jun 01 '18 at 23:55

There is no literal Dictionary in Java, the combination you're looking for is a List<Map<String, String>> Both List and Map are interfaces, so they can't be directly instantiated. In your case, the concrete classes for those are varied, but either ArrayList or LinkedList for List and HashMap for Map.

You can get something vaguely similar with anonymous classes:

List<Map<String, String>> myDict = new ArrayList<Map<String, String>>() {{
    add(new HashMap<String, String>() {{
        put("title", "some title");
    }});
}}

Is there a Java version of the creating an array of dictionaries like in Swift

3 Answers3