Load html errors undefined property File

Question

in the following code take 4 errors on 2 bold lines
mdapp, Layer 'inputpage', Frame 1, Line 25 1046: Type was not found or was not a compile-time constant: File.
mdapp, Layer 'inputpage', Frame 1, Line 26 1046: Type was not found or was not a compile-time constant: File.
mdapp, Layer 'inputpage', Frame 1, Line 25 1120: Access of undefined property File.
mdapp, Layer 'inputpage', Frame 1, Line 26 1120: Access of undefined property File.
//Copy the html file outside the app directory
var templateFile:File = File.applicationDirectory.resolvePath( "adview.html" );
var workingFile:File = File.createTempFile();
templateFile.copyTo( workingFile, true );
try
    webView.loadURL( workingFile.url );
where is my fault?

Answer 1

applicationDirectory is used for files you package with your app. If you downloaded or generated the file then you might want applicationStorageDirectory.
You also should check the .exists property before trying to do anything with a file.
templateFile:File = File.applicationDirectory.resolvePath( "adview.html" );
if (templateFile.exists)
    // exists, do stuff
else
     trace('oops file does not exist');
Never try to save to applicationDirectory either, use applicationStorageDirectory or one of the other temp cache paths in the documentation.