<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
  layout="vertical"
  horizontalAlign="center" verticalAlign="middle"
  currentState="FtoC">
  
  <mx:Script>
    <![CDATA[
      private const C_INPUT_TEXT:String = "Geben Sie eine Temperatur in Celsius ein:";
      private const F_INPUT_TEXT:String = "Geben Sie eine Temperatur in Fahrenheit ein:";
      private const CF_STATE:String = "CtoF";
      private const FC_STATE:String = "FtoC";
      
      private function convertTemp():void
      {
        var inputTemp:Number = parseFloat(inputTempField.text);
        var outputTemp:Number;
        
        switch (currentState) {
          case CF_STATE:
            outputTemp = convertCtoF(inputTemp);
            outputTempField.text = outputTempFormatter.format(outputTemp);
            outputTempField.text += "°F";
            break;
          case FC_STATE:
            outputTemp = convertFtoC(inputTemp);
            outputTempField.text = outputTempFormatter.format(outputTemp);
            outputTempField.text += "°C";
            break;
          default:
            throw new Error("Unerwarteter Zustand");
        }
      }
      
      private function clearTemp():void
      {
        inputTempField.text= "";
        outputTempField.text = "";
      }
      
      private function convertCtoF(celsius:Number):Number
      {
        return ((celsius * 9) / 5 + 32);
      }
      
      private function convertFtoC(fahrenheit:Number):Number
      {
        return 5/9 * (fahrenheit - 32);
      }
    ]]>
  </mx:Script>
  
  <mx:Style>
    .outputTemp { fontsize: 18; fontweight: bold; color: red}
  </mx:Style>
  
  <mx:states>
    <mx:State name="{FC_STATE}" enterState="convertTemp()">
      <mx:SetProperty target="{inputLabel}" name="text" value="{F_INPUT_TEXT}"/>
    </mx:State>
    <mx:State name="{CF_STATE}" enterState="convertTemp()">
      <mx:SetProperty target="{inputLabel}" name="text" value="{C_INPUT_TEXT}"/>
    </mx:State>
  </mx:states>
  
  <mx:NumberValidator source="{inputTempField}" property="text" triggerEvent="change" valid="convertTemp()" invalid="clearTemp()"/>
  <mx:NumberFormatter id="outputTempFormatter" precision="2"/>
  
  <!-- Layout --> 
  <mx:Panel title="Temperaturumrechnung" layout="vertical" horizontalAlign="middle">
    <mx:HBox horizontalAlign="center" verticalAlign="middle">
      <mx:Label id="inputLabel"/>
      <mx:TextInput id="inputTempField" maxChars="5"/>
      <mx:Spacer width="10"/>
      <mx:Text id="outputTempField" styleName="outputTemp" width="100"/>
    </mx:HBox>
    <mx:HBox horizontalAlign="center" creationComplete="conversionMode.selectedValue=currentState;">
      <mx:RadioButtonGroup id="conversionMode" change="currentState = conversionMode.selectedValue as String"/>
      <mx:RadioButton group="{conversionMode}" label="Fahrenheit zu Celsius" value="FtoC"/>
      <mx:RadioButton group="{conversionMode}" label="Celsius zu Fahrenheit" value="CtoF"/>
    </mx:HBox>
  </mx:Panel>
</mx:Application>