question: private File buildFile ( File file , String fileName , String type ) { StringBuilder fileNameBuilder = new StringBuilder ( ) ; fileNameBuilder . append ( file . getPath ( ) ) ; fileNameBuilder . append ( File . separator ) ; fileNameBuilder . append ( type ) ; fileNameBuilder . append ( fileName ) ; return new File ( fileNameBuilder . toString ( ) ) ; }
target:  Builds the cached file method into the disk cache.