The skip() method may skip a smaller number of bytes than requested. Check the returned value to find out if it was the case or not. Example:
public class Foo {

   private FileInputStream _s = new FileInputStream("file");

   public void skip(int n) throws IOException {
      _s.skip(n); // You are not sure that exactly n bytes are skipped
   }

   public void skipExactly(int n) throws IOException {
      while (n != 0) {
         long skipped = _s.skip(n);
         if (skipped == 0)
            throw new EOFException();
         n -= skipped;
      }
   }

This rule is deprecated, use {rule:squid:S2674} instead.