Android Marker的图标

嗨,我有一段代码,每当我按下添加标记按钮时,它都会在地图上添加标记。每次在地图上添加标记时,我如何更改标记图标?非常感谢。

   function initialize() {
    var myLatlng = new google.maps.LatLng(40.779502, -73.967857);

    var myOptions = {
        zoom: 7,
        center: myLatlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    map = new google.maps.Map(document.getElementById("map"), myOptions);
    TestMarker();
      }
  google.maps.event.addDomListener(window, 'load', initialize);


  function addmarker(location) {
    marker = new google.maps.Marker({
        position: location,
        draggable:true,
        map: map
        for()
     });
    }

// Testing the addMarker function
function TestMarker() {
       CentralPark = new google.maps.LatLng(40.779502, -73.967857);
       addmarker(CentralPark);
  }