public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    LatLng CCU = new LatLng(23.558581, 120.471984);
    mMap.addMarker(new MarkerOptions().position(CCU).title("施工").icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN)));

    mMap.getUiSettings().setCompassEnabled(true);
    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(CCU, 15));


   mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener()
   {
        @Override
        public void onMapClick(LatLng point)
        {

            AlertDialog.Builder builder;
            AlertDialog alertDialog;
            Context mContext = Contact2Fragment.this.getContext();
            LayoutInflater vi = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            View view = vi.inflate(R.layout.alertdialog, null);
            RadioGroup rg = (RadioGroup)view.findViewById(R.id.RadioGroup);
            lat = point.latitude;
            lon = point.longitude;
            final EditText editText = (EditText) view.findViewById(R.id.input);

            builder = new AlertDialog.Builder(mContext);
            builder.setView(view);

            builder.setNeutralButton("Cancel", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            });

            builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {

                    Context mContext = Contact2Fragment.this.getContext();
                    LayoutInflater vi = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                    View view = vi.inflate(R.layout.alertdialog, null);
                    RadioGroup rg = (RadioGroup)view.findViewById(R.id.RadioGroup);
                    String m_Text = editText.getText().toString();

                    final MarkerOptions marker = new MarkerOptions().position(new LatLng(lat,lon)).title( m_Text);
                    switch (rg.getCheckedRadioButtonId()){
                        case R.id.radioButton_Green:{
                            marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
                            break;
                        }
                        case R.id.radioButton_Yellow: {
                            marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_YELLOW)) ;
                            break;
                        }
                        case R.id.radioButton_Red: {
                            marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
                            break;
                        }
                    }
                    rg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
                        @Override
                        public void onCheckedChanged(RadioGroup group, int checkedId) {
                        switch (checkedId){
                            case R.id.radioButton_Green:
                                group.check(R.id.radioButton_Green);
                                marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
                                break;
                            case R.id.radioButton_Yellow:
                                group.check(R.id.radioButton_Yellow);
                                marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_YELLOW)) ;
                                break;
                            case R.id.radioButton_Red:
                                group.check(R.id.radioButton_Red);
                                marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)) ;
                                break;
                        }
                        }
                    });
                    dialog.dismiss();
                    mMap.addMarker(marker);
                }
            });
            alertDialog = builder.create();
            alertDialog.setTitle("Describe the situation");
            alertDialog.show();
        }
  });
}