Most applications require the use of strings in one way or another. Strings are required for building SQL statements when accessing a database, for example. Knowing how to manipulate strings is useful in analyzing requests from Web clients and in constructing a response for the client.
Strings are reference types. You’ve been learning about reference types little by little in each chapter. The category of reference types includes types you define with the class keyword. As you may recall, you have to create an object before you can use a variable of the type. For example:
Account acct = new Account();
Before you create an object, the variable holds the value of
null. The same rule holds true for strings. String variables when ...