public class Map2 extends AppCompatActivity implements OnMapReadyCallback {
    private List<LatLng> dataLatlng = new ArrayList<>();
    private double a, b;
    private LatLng data;
    private int incrementNext = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_map2);
        Button btnNext; // ini maksudnya mau dibuat next gak? atau gimana aku cuma nerka
        btnNext = (Button) findViewById(R.id.btn_map_dua)) // ini deklarasi view button

        // add data manual
        a = -8.18330000;
        b = 131.08330000;
        data = new LatLng(a, b);
        dataLatLng.add(data);

        a = -8.09546270;
        b = 112.16090560;
        data = new LatLng(a, b);
        dataLatLng.add(data);


        SupportMapFragment mapFragment =
                (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map_dua);
        mapFragment.getMapAsync(this);
    }

    /**
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we
     * just add a marker near Africa.
     */
    @Override
    public void onMapReady(GoogleMap map) {

        btnNext.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (increment == 0) {
                  cameraMover(dataLatLng.get(increment)); // biar lebih sedikit nulis code, jadi dibuatin method
                  increment += 1;
                } else if (increment == 1) {
                  cameraMover(dataLatLng.get(increment));
                  increment -= 1;
                }
            }
        });

        foreach(int data : dataLatlng) {
          map.addMarker(new MarkerOptions().position(data).title("Mukidi Get Data Tambal Ban"));
        }
    }

    private void cameraMover(LatLng data) {
      map.moveCamera(CameraUpdateFactory.newLatLngZoom(data, 18));
    }
}