Add element to Map of String, Arraylist

Question

Working with the Google Maps API for Android (v2), I am trying to store some country Polygon approximations into a data structure, particularly, a map with String as keys (name of the country) and an ArrayList of PolygonOptions.

This var is private and declared by:

private Map<String, ArrayList<PolygonOptions>> worldMap;

But my code crashes when I try to fill it with a PolygonOption, in the following function:

private void addSomeCountry() {
        ArrayList <PolygonOptions> MyPoli = new ArrayList<PolygonOptions>();
        PolygonOptions rectOptions = new PolygonOptions()
                .add(new LatLng(42.569962, 1.78172 ))
                .add(new LatLng(42.509438, 1.723611))  
                .add(new LatLng(42.601944, 1.445833))  
                .add(new LatLng(42.569962, 1.78172)) 
                .fillColor(Color.TRANSPARENT)
                .strokeColor(Color.CYAN);
        MyPoli.add(rectOptions);
        worldMap.put("Andorra", MyPoli);
    }

Specifically, it crashes with the following error:

04-04 21:20:30.335  22562-22562/otorrillas.geography E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: otorrillas.geography, PID: 22562
Caused by: java.lang.NullPointerException
             at otorrillas.geography.DataSaver.addSomeCountry(DataSaver.java:49)
             at otorrillas.geography.DataSaver.onCreate(DataSaver.java:32)

Am I doing something wrong?

Eran · Accepted Answer · 2015-04-04 19:29:26Z

2

I don't see you initializing worldMap anywhere.

private Map<String, ArrayList<PolygonOptions>> worldMap = new HashMap<>();

should do.

answered Apr 4, 2015 at 19:29

Eran

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