Java™ How To Program (Early Objects), Tenth Edition

Testing the Generic Stack Class of Fig. 20.7

Now, let’s consider the application (Fig. 20.9) that uses the Stack generic class (Fig. 20.7). Lines 12–13 in Fig. 20.9 create and initialize variables of type Stack<Double> (pronounced “Stack of Double”) and Stack<Integer> (pronounced “Stack of Integer”). The types Double and Integer are known as the Stack’s type arguments. The compiler uses them to replace the type parameters so that it can perform type checking and insert cast operations as necessary. We’ll discuss the cast operations in more detail shortly. Lines 12–13 instantiate doubleStack with a capacity of 5 and integerStack with a capacity of 10 (the default). Lines 16–17 and 20–21 call methods testPushDouble (lines 25–36), testPopDouble ...