CHAPTER 5 — Scanners with One Character Pushback

The scanner in the previous chapter worked by reading characters one by one, processing each one before reading the next. It was always able to process the character it had just read. Often with scanners this is not the case. Sometimes a scanner must read one character beyond the end of a token in order to determine that the token has ended. This chapter shows how scanners do this.

Chapter Topics:

• When one character push-back is needed
• How to implement push-back by extending BufferedReader
• The Java class PushbackReader
• An example scanner using push-back