How can I determine if a file is a PDF file?

Question

I am using PdfBox in Java to extract text from PDF files. Some of the input files provided are not valid and PDFTextStripper halts on these files. Is there a clean way to ch

Answer 1

Pdf files begin "%PDF" (open one in TextPad or similar and take a look)

Any reason you can't just read the file with a StringReader and check for this?