Store set of data in java, like python's dict

Question

I have a set of data that I want to store in a simple variable. Basically a list of fifteen names with location coordinates. In Python I'd create a dict, something like:

locations = {'Location1': [lat1, lon1], 'Location2': [lat2, lon2], ...}

So that way I can later call the coordinates by using the location name as key:

coords = locations['Location1']

Any equivalent to do this in Java? I basically want to define these locations as a constant in my code.

EDIT after receiving the first very fast replies:

I have now added this:

private class coordinates {
    private Long lat;
    private Long lon;
    public Long getLat() {
        return lat;
    }
    public void setLat(Long lat) {
        this.lat = lat;
    }
    public Long getLon() {
        return lon;
    }
    public void setLon(Long lon) {
        this.lon = lon;
    }
}

private final static Map<String, coordinates> LOCATIONS;

The last line is of course incomplete; I'm at a loss on how to populate this thing, without using extra temporary variables to access the two setters, resulting in several lines of code for every single set of values.

A Map containing a custom object with lat and lon fields. – Sotirios Delimanolis Mar 13 '13 at 16:43 — Sotirios Delimanolis, Mar 13 '13 at 16:43

score 3 · Accepted Answer · edited May 23 '17 at 11:51

3

You can use a Map in java:

Like: Map<LocationObject, CoordinateObject>

Where CoordinateObject has latitude and longitude as attributes

class CoordinateObject {
   //longitude;
   //latitude;
}

Related Post

edited May 23 '17 at 11:51

Community

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answered Mar 13 '13 at 16:43

PermGenError

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I was hoping for something that would not add a complete class and a lot more clutter to my program. And how to populate this map? – Wouter Mar 13 '13 at 17:00
http://stackoverflow.com/questions/120283/working-with-latitude-longitude-values-in-java might be helpful then. – PermGenError Mar 13 '13 at 17:01
Not applicable in this case; I just need to store the numbers so later I can retrieve them to put markers on a map, no need for any calculations. – Wouter Mar 13 '13 at 17:08
@Wouter in that case using Map with Custom Coordinates class is a way to go. – PermGenError Mar 13 '13 at 17:09

score 3 · Answer 2 · answered Mar 13 '13 at 16:43

3

In Java, the correct data structure for this would be a Map.

answered Mar 13 '13 at 16:43

Dominik Sandjaja

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score 0 · Answer 3 · answered Mar 13 '13 at 17:25

0

I think I found a more convenient solution by adapting some other answers on StackOverflow, without the trouble of having to create a separate object (and realised I was using the wrong type):

private final static Map<String, Double[]> LOCATIONS;
static
{
    LOCATIONS = new Map<String, Double[]>();
    LOCATIONS.put("Central_Western", new Double[] {22.288262, 114.140138});
    LOCATIONS.put("Eastern", new Double[] {22.286078, 114.216957});
}

Now I should be able to call Double[] loc = LOCATIONS["Central_Western"] and have an array of two numbers.

OK haven't tested it yet... trying such little things is so hard in Java/Android... I so miss Python's console...

answered Mar 13 '13 at 17:25

Wouter

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hmm, the thing is what if someone accidentally populates your double array with an extra decimal number ??. java is Object Oriented. and i think you should use a class body for the co-ordinates. :) – PermGenError Mar 13 '13 at 17:32
That is impossible as it is a static map, and all data is hard-coded. It is meant to be read-only. And this way it's reasonably clutter-free, and it works. Furthermore no clue on how to easily populate (and read) the data in the map if the value is a custom object. – Wouter Mar 13 '13 at 18:03

Store set of data in java, like python's dict

3 Answers3