Chapter 4

Arrays and Strings

WHAT YOU WILL LEARN IN THIS CHAPTER

  • What arrays are and how you declare and initialize them
  • How you access individual elements of an array
  • How you can use individual elements of an array
  • How to declare arrays of arrays
  • How you can create arrays of arrays with different lengths
  • How to create String objects
  • How to create and use arrays of String objects
  • What operations are available for String objects
  • What StringBuffer objects are and how they relate to operations on String objects
  • What operations are available for StringBuffer objects

In this chapter you start to use Java objects. You are first introduced to arrays, which enable you to deal with a number of variables of the same type through a single variable name, and then you look at how to handle character strings. Some of what I discuss in this chapter relates to objects, and as I have not yet covered in detail how you define a class (which is an object type definition), I have to skate over some aspects of how objects work, but all is revealed in Chapter 5.

ARRAYS

With the basic built-in Java data types that you’ve seen in the previous chapters, each identifier corresponds to a single variable. But when you want to handle sets of values of the same type — the first 1,000 primes, for example — you really don’t want to have to name them individually. What you need is an array.

You should first have a rough idea of what an array is and how it works. An array is an object that is a named set of variables ...

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