Chapter 5. Strings

Everyone has a logger and most of them are string pigs.

Kirk Pepperdine

Strings have a special status in Java. They are the only objects with:

  • Their own operators (+ and +=)

  • A literal form (characters surrounded by double quotes, e.g., "hello")

  • Their own externally accessible collection in the VM and class files (i.e., string pools, which provide uniqueness of String objects if the string sequence can be determined at compile time)

Strings are immutable and have a special relationship with StringBuffer objects. A String cannot be altered once created. Applying a method that looks like it changes the String (such as String.trim( )) doesn't actually do so; instead, it returns an altered copy of the String. Strings are also final, and so cannot be subclassed. These points have advantages and disadvantages so far as performance is concerned. For fast string manipulation, the inability to subclass String or access the internal char array can be a serious problem.