My-Location Button of GoogleMaps v2 Android, not displayed

The myLocationButtonEnabled is true by default and shown when the setMyLocationEnabled layer is enabled.

try this:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

    // Add this line
    map.setMyLocationEnabled(true);

    locManager = (LocationManager)getSystemService(LOCATION_SERVICE);
    providersList = locManager.getAllProviders();
    provider =locManager.getProvider(providersList.get(0));
    precision = provider.getAccuracy();
    req = new Criteria();
    req.setAccuracy(Criteria.ACCURACY_FINE);        
    inside = false;

    //map.getUiSettings().setMyLocationButtonEnabled(true);

    buildPolygon();
    drawPolygon();
    startLocalization();
}

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setMyLocationEnabled Documentation
setMyLocationButtonEnabled Documentation

Add the following line.

Kotlin:

map.isMyLocationEnabled = true

map is a GoogleMap object.

(More detailed answer(s) in this question: https://stackoverflow.com/a/15142091/11211963 )

just add map.setMyLocationEnabled(true); after create your map

map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

to be like this

map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

map.setMyLocationEnabled(true);