Flex LineChart 动态添加线(LineSeries)及颜色

LineChart控件如何动态添加线，并设置线的颜色呢。找了很多资料都没合适的，不容易呀，下面直接上代码。

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" creationComplete="init()">
<fx:Declarations>
<!-- 将非可视元素（例如服务、值对象）放在此处 -->
<mx:Stroke id = "s1" color="blue" weight="2"/>
</fx:Declarations>
<s:layout>
<s:VerticalLayout/>
</s:layout>
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
import mx.charts.series.LineSeries;
[Bindable]
public var coll:ArrayCollection = new ArrayCollection([
{Date:"2011-12-1",Value:2},
{Date:"2011-12-2",Value:4},
{Date:"2011-12-3",Value:5},
{Date:"2011-12-4",Value:9},
{Date:"2011-12-5",Value:6}
]);

protected function init():void{
var array:Array = new Array();

var lineSeries1:LineSeries=new LineSeries(); //设置图表的系列
lineSeries1.xField="Date"
lineSeries1.yField = "Value";
lineSeries1.displayName="时间趋势图";
lineSeries1.setStyle("form", "curve");
lineSeries1.setStyle("lineStroke",s1);
array.push( lineSeries1 );
myChart.series = array//给图表系列赋值
}
]]>
</fx:Script>
<mx:Legend dataProvider="{myChart}" height="20"/>
<mx:LineChart id="myChart" dataProvider="{coll}" width="400" height="360" showDataTips="true">
<mx:verticalAxis>
<mx:LinearAxis id="laxis" autoAdjust="true" baseAtZero="false" />
</mx:verticalAxis>
<mx:horizontalAxis>
<mx:CategoryAxis id="ca"
dataProvider="{coll}"
categoryField="Date"
/>

</mx:horizontalAxis>
<mx:horizontalAxisRenderers>
<mx:AxisRenderer axis="{ca}"
canDropLabels="true" />
</mx:horizontalAxisRenderers>
<mx:series>
</mx:series>
</mx:LineChart>
</s:Application>