static void deleteDir( File directory){
		if( directory == null ){
			return ;
		}
		if( directory.isFile()){
			directory.delete();
		}
		else if( directory.isDirectory() ){
			File[] subFiles = directory.listFiles();
			if( subFiles != null ){
				for( int i=0; i<subFiles.length; i++){
					deleteDir( subFiles[i]);
				}
				directory.delete();
			}
		}
	}