Android GoogleMaps API: IndexOutOfBoundsException in PolyUtil.decode()

Question

I have an Android app with a GoogleMap and I want to draw a Polyline on it. For that I'm using PolyUtils.decode(). But if it is called with my encoded String, I get an IndexOutOfBoundsException.

This is my piece of code:

private void drawPolyLine() {
    List<Trail> trails = mVehicle.getTrails();
    for (Trail trail : trails) {
        String encodedPolyline = trail.getTrail();
        String color = trail.getColor();
        List<LatLng> locations = PolyUtil.decode(encodedPolyline);
        Polyline line = mMap.addPolyline(new PolylineOptions()
                .add(locations.toArray(new LatLng[locations.size()]))
                .width(5)
                .color(parseColor(color)));
    }
}

The encoded String that is passed to PolyUtil.decode() is:

"0ee24344-9647-4592-92e7-a51b71008f4b"

And the stack trace looks like this:

java.lang.StringIndexOutOfBoundsException: length=36; index=36
 E/AndroidRuntime:     at java.lang.String.indexAndLength(String.java:500)
 E/AndroidRuntime:     at java.lang.String.charAt(String.java:494)
 E/AndroidRuntime:     at com.google.maps.android.PolyUtil.decode(PolyUtil.java:313)
 E/AndroidRuntime:     at net.my.domain.views.fragments.VehicleMapFragment.drawPolyLine(VehicleMapFragment.java:140)
 ...

What might possibly cause an IndexOutOfBoundsException like this? Is it my String that is invalid? How can I check whether or not an encoded Polyline String is valid? Can someone post me a valid example of a valid encoded Polyline?

Answer 1

The encoded String that you are passing to PolyUtil.decode() does not seem to be a valid encoded polyline. It seems to be a UUID.

The IndexOutOfBoundsException is caused the by an invalid encoded polyline.

Here is an example of encoding/decoding a polyline:

// Encoding
List<LatLng> locations2Encode = new ArrayList<LatLng>();
locations2Encode.add(new LatLng(40.1d, -3.1d));
locations2Encode.add(new LatLng(40.2d, -3.2d));
locations2Encode.add(new LatLng(40.3d, -3.3d));
locations2Encode.add(new LatLng(40.4d, -3.4d));
String encodedPolyline = PolyUtil.encode(locations2Encode);

// Decoding
List<LatLng> locations = PolyUtil.decode(encodedPolyline);

In this case the String representing the encoded polyline is

_`wsF~m|Q_pR~oR_pR~oR_pR~oR

According to the documentation it seems that there is no way to check if a encoded polyline is valid rather that decoding it.

You can find more examples and more info about encoding and decoding polylines in the documentation.