This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
some observations here, 1. when parse quadLine, you could use "+-" as delimiters. 2. put token-getting code inside a while loop as user may not always enter a fully quadratic function eg, 2x^2 - 8, ie : you don't always have 3 tokens to fetch.