10. Overview

• Strings are immutable. “Changing” functions like s.toUpperCase() actually return a copy; they do not affect the original.

• Understand the box and arrow diagrams on page 269.

• String methods (summarized on page 271, Figure 10-3):

  • s.length()
  • s.charAt(idx): but note the answer is a char not a String.
  • s.substring(start)
  • s.substring(start,end)
  • s.equals(otherString)
  • s.compareTo()
  • s.indexOf("wanted")

• Useful in real life: trim, replace, toLowerCase.

10.5: Formatting

Lots of detail on how to get a number to appear exactly the way you want it. Read if you are advanced.

Tutorial on printf, Tutorial on formatting numbers.

10.6: Numbers to Strings

This section includes basic parsing as well as how to handle “exceptions” that may occur.

• double x = Double.parseDouble("3.14159")
• int a = Integer.parseInt("121")